Secondarily contained in-dispenser sump/pan system and method for capturing and monitoring leaks

ABSTRACT

An in-dispenser leak pan provided inside the housing of a fuel dispenser. The leak collection chamber collects any fuel that leaks from fuel-handling components located inside the fuel dispenser above the pan. The pan is secondarily contained by an outer pan or container such that an interstitial space is formed therebetween. If a breach exists in the top part of the pan, the captured leaked fuel will be contained in by the outer pan in the interstitial space. The interstitial space of the pan is drawn under a vacuum level using a vacuum-generating source to monitor for leaks. If a leak is detected, a control system may generate an alarm and/or cause the submersible turbine pump to stop supplying fuel, or cause the dispenser product line shear valves to close, thereby only stopping fuel flow to the individual fuel dispenser containing the leak.

RELATED APPLICATION(S)

This application is a Continuation-In-Part of U.S. patent applicationSer. No. 11/411,182 entitled “VACUUM-ACTUATED SHEAR VALVE DEVICE,SYSTEM, AND METHOD, PARTICULARLY FOR USE IN SERVICE STATIONENVIRONMENTS,” filed on Apr. 25, 2006, and is a Continuation-In-Part ofU.S. patent application Ser. No. 10/829,659 entitled “LEAK CONTAINER FORFUEL DISPENSER,” filed on Apr. 22, 2004, and claims priority to both ofthese applications and U.S. Provisional Patent Application No.60/674,743 entitled “VACUUM-OPERATED SHEAR VALVE WITH FLOAT AND SERVICESWITCH AND FILTER INTERLOCK DEVICE, SYSTEM, AND METHOD,” filed on Apr.26, 2005, all of which are incorporated herein by reference in theirentireties.

This application is also related to U.S. Pat. Nos. 6,834,534; 6,977,042;6,978,660; 6,978,661; and 7,010,961, U.S. Patent Application PublicationNos. 2004/0045343 A1; 2005/0039518 A1; 2005/0145015 A1; 2005/0145016 A1;2005/0247111 A1; 2005/0236044 A1; and 2005/0236045 A1; U.S. patentapplication Ser. Nos. 11/255,421; 11/354,394; and 11/354,886; and U.S.Provisional Patent Application No. 60/654,390; all of which areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention is related to a secondary containment monitoringand control system for monitoring secondarily-contained fuel-handlingcomponents for leak detection and prevention. Various control devicesare employed to control the fuel-handling components and fuel flow inresponse to a leak or other alarm or safety condition to mitigate thepotential for leaking fuel to the environment.

BACKGROUND OF THE INVENTION

In service station environments, fuel is typically delivered to fueldispensers from underground storage tanks (USTs), sometimes referred toas fuel storage tanks. USTs are large containers located beneath theground that hold fuel. A separate UST is provided for each fuel type,such as low octane gasoline, high-octane gasoline, and diesel fuel. Inorder to deliver the fuel from the USTs to the fuel dispensers, asubmersible turbine pump (STP) is typically provided that pumps the fuelout of the UST and delivers the fuel through a main fuel piping conduitthat runs beneath the ground in the service station. Other types ofpumps other than a STP, such as a self-contained pump within thedispenser housing for example, may be employed.

Due to environmental and possible regulatory requirements governingservice stations, fuel-handling components that handle fuel or vapor andwould leak the fuel or vapor to the environment if a leak existed mayneed to be secondarily contained. Examples of fuel-handling componentsinclude, but are not limited to fuel storage tanks, fuel piping conduitsthat carry fuel, STPs, main fuel piping, branch fuel piping, sumps,shear valves, and dispenser piping. Secondary containment is typicallyprovided in the form of a sealed outer piping or outer container thatsurrounds the fuel-handling component whereby a space, called an“interstitial space” is formed between the fuel-handing component andthe outer container or piping. If a leak occurs in the fuel-handlingcomponent, the leak is trapped in the interstitial space provided by theouter piping or outer container. Thus, the leak is prevented fromleaking to the environment. The secondary containment must periodicallybe checked and evacuated.

It is possible that the secondary containment could also contain a leakunknown to service station operators. In this instance, if a leak wereto occur in a fuel-handling component, the leak may escape to theenvironment through the leak in the secondary containment. For example,if the fuel-handling component is a double-walled fuel piping, whereinan outer piping surrounds and inner piping that carries fuel, and a leakexists in both the inner and outer piping, fuel from the inner pipingmay leak to the environment through the outer piping. Thus, withoutmonitoring of the interstitial spaces provided by the secondarycontainment, it is possible that a leak can occur to the environmentwithout being detected. The STP will continue to operate as normal,drawing fuel from the UST and providing fuel to the source of the leak.

Recent proposed changes in state and federal regulations will tightenthe requirements to contain leaks via secondary containment and willfurther require better leak detection so that environmental damage maybe minimized. As a result, it is becoming imperative that all potentialleak sources be evaluated and steps taken to detect and contain leaks inthe piping systems. If the interstitial space of the secondarilycontained fuel-handling components can be monitored to detect a leak orbreach in either the fuel-handling component or the outer containment, abreach can typically be detected before the leak could escape to theenvironment.

One method of monitoring the interstitial space of secondarily containedfuel-handling components for leaks is by drawing a vacuum level in theinterstitial space. Examples of such systems are the aforementioned U.S.Pat. Nos. 6,834,534; 6,977,042; 6,978,661; and 7,010,961, U.S. PatentApplication Publication Nos. 2004/0045343 A1; 2005/0039518 A1;2005/0145015 A1; 2005/0145016 A1; and 2005/0247111 A1; and U.S. patentapplication Ser. No. 11/255,421. In these systems, a vacuum-generatingsource, which may be from a siphon port on the STP for example, draws avacuum in the interstitial space. Thereafter, the interstitial space ismonitored for pressure variations. If a sufficient pressure variationoccurs, this is an indication that either the fuel-handling component orthe outer containment has incurred a leak or breach due to the ingressor egress of fuel and/or air into the interstitial space from either thefuel-handling component or from the outside air.

The aforementioned U.S. Patent Publication Nos. 2005/0236044 A1; and2005/02346045 A1 (hereinafter the “'044 Application” and the “'045Application,” respectively) provide for an in-dispenser pan or sump thatcaptures leaked fuel from fuel-handling components located above the paninside the fuel dispenser. The advantages-of providing this pan aredisclosed in the '044 and '045 Applications. However, the pan is notsecondarily contained, and thus any fuel leaks captured by the pan willleak to the bottom of the fuel dispenser and possibly to the environmentif a breach or leak is contained in the pan.

SUMMARY OF THE INVENTION

The present invention involves the use of an in-dispenser pan or sump asan alternative to a below ground dispenser sump. In this manner, anyleaks that occur in fuel-handling components located above thein-dispenser pan are captured. An in-dispenser sump may be used toeffectively provide secondary containment for capturing leaks forfuel-handling components where providing of secondary containment byother methods is not possible or impracticable for space and/or costreasons. The in-dispenser sump is comprised of a plate that runs acrossthe width of the fuel dispenser. The plate contains protruding edgesthat tilt upward on the far ends of the plate to capture leaks thatoccur above the plate. The plate is slanted upward on both sides so thatwhen a leak is captured by the plate, gravity will pull the leak towardsthe center of the plate.

The plate contains orifices for the internal fuel dispenser piping torun through the plate to other components of the fuel dispenser. Thepipings are typically sealed in the orifice with a potting or epoxycompound. In this manner, any leaked fuel captured by the plate willgravitate and collect in the center of the plate without leaking throughthe orifices. A low level liquid sensor is placed proximate to thecenter of the plate at the lowest level to detect any presence of leakedfuel. A high liquid sensor may also be placed similarly, but at adesignated liquid level to detect when the leaks accumulate to a certainliquid level in the in-dispenser sump as a redundancy sensor in case thelow liquid level sensor fails. Both low level liquid sensor and the highliquid level sensor are communicatively coupled to a control system todetect the leaks.

Because the plate acts to capture leaks, the plate can also besecondarily contained in the event the plate is breached or contains aleak in order to prevent the captured fuel from reaching theenvironment. Thus, the in-dispenser sump is comprised of a double-walledplate structure. The main plate is supported by an outer, secondaryplate. An interstitial space is formed by the space between the mainplate and the secondary plate. In this manner, the interstitial spacewill hold any leaks that occur as a result of a breach or leak in themain plate when a leak has occurred in a fuel-handling component locatedabove the main plate. Because of the interstitial space provided, thisinterstitial space can be monitored for leaks or breaches using avacuum-generating source that is also used for monitoring of leaks inother fuel-handling components.

In one embodiment, the interstitial space of the in-dispenser sump isfluidly coupled to the vacuum conduit, that is connected to the vacuumactuator of a product line shear valve. A leak in the in-dispenser sumpwill cause a loss of vacuum at the vacuum actuator, that will in turnautomatically cause the shear valve to close, thereby preventing morefuel from reaching the leaky fuel-handling component that is causing theleak.

In another embodiment, a interstitial liquid sensor may also be fluidlycoupled to the in-dispenser interstitial space. The sensor may providean electronic signal to a control system to detect a leak in thein-dispenser sump interstitial space. The control system may generate analarm and/or generate either an electronic or pneumatic signal to causethe vacuum actuator to close the product line shear valves that aresupplying fuel to the fuel-handling component whose leak is beingcaptured by the in-dispenser sump.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is an illustration of a typical fuel dispenser in the prior art;

FIG. 2 is an illustration of the fuel dispenser illustrated in FIG. 1showing the internal components of the fuel dispenser and the interfacebetween a shear valve, a branch fuel piping, internal fuel dispenserpiping, and a dispenser sump in the prior art;

FIG. 3 is an illustration of a secondary containment system in a servicestations in accordance with the present invention for capturing andmonitoring leaks in fuel-handling components.

FIG. 4 is an illustration of a vacuum actuated shear valve in accordancewith one vacuum actuated shear valve embodiment of the presentinvention;

FIG. 5 is an illustration of a vacuum actuated shear valve in accordancewith another vacuum actuated shear valve embodiment of the presentinvention;

FIG. 6 is an illustration of a vacuum actuated shear valve in accordancewith a third vacuum actuated shear valve embodiment of the presentinvention;

FIG. 7 is an illustration of a vacuum actuated shear valve systememploying a flow switch, service switch, and filter interlock to controlthe vacuum actuated shear valve in accordance with one embodiment of thepresent invention;

FIG. 8 is a flowchart illustration of the process to control the openingand closing of the vacuum actuated shear valve in response to detectionof a loss of vacuum in accordance with the system in FIG. 7;

FIG. 9 is a flowchart illustration of the process to control the openingand closing of the vacuum actuated shear valve based on a servicesetting;

FIG. 10 is a flowchart illustration of the process to control theopening and closing of the vacuum actuated shear valve to a filterinterlock activated when servicing a filter in the fuel dispenser;

FIG. 11 is an illustration of two embodiments of a secondarily containedand monitored fuel dispenser containment sump;

FIG. 12 is an illustration of a secondarily contained fuel dispenserwith containment sump in accordance with the system of FIG. 3 withoperational interfaces for capturing and monitoring a leak;

FIG. 13 is an illustration of a dispenser sensor module (DSM) used tointerface with the secondary containment of fuel-handling components tocontrol vacuum level and monitor for leaks in accordance with thepresent invention;

FIG. 14 is a pneumatic diagram illustrating the operational componentsof the secondary containment system according to the present invention;

FIG. 15 is an electrical division diagram illustrating the operationalcomponents of the secondary containment system according to the presentinvention;

FIG. 16 is a communications diagram illustrating the operationalcomponents of the secondary containment system according to the presentinvention;

FIG. 17 is an illustration of a shear valve controller for controllingthe operation of the vacuum actuated shear valve according to oneembodiment of the present invention;

FIG. 18 is an illustration of the shear valve controller housing for theshear valve controller illustrated in FIG. 17; and

FIG. 19 is a cross-sectional illustration of the shear valve controllerillustrated in FIGS. 17 and 18.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In general, the present invention is a secondary containment monitoringand control system employing various features and enhancements tocontrol vacuum level used for monitoring and detecting leaks insecondarily contained fuel-handling components. The secondarycontainment monitoring system provides a vacuum-generating source thatgenerates a vacuum level in interstitial spaces of fuel-handlingcomponents formed as a result of space provided between an inner fuelcarrying component surrounded by an outer secondary containment. Thepressure variations of the interstitial space are monitored for possibleleaks. When a leak is detected the system controls vacuum replenishmentand/or the automatic closing of a vacuum actuated product line shearvalve. Thus, the source of fuel is cut off from the potential leaksource.

Examples of related and predecessor systems are provided in U.S. PatentApplication Publication Nos. US 2004/0045343 A1; US 2005/0039518 A1; US2005/0145016 A1; and US 2005/0247111 A1; U.S. Pat. Nos. 6,834,534;6,997,042; 7,010,961; 6,978,660; and 6,978,661 (hereinafter the “'343Application,” “'581 Application,” “'016 Application,” “'111Application,” “'534 Patent,” “'042 Patent,” “'961 Patent,” “'660Patent,” and the “'661 Patent,” respectively), all of which areincorporated herein by reference. The '534 Patent monitors the secondarycontainment of a fuel storage tank. The '343, '518, '016, and '111Applications monitor the secondary containment of fuel piping. The '961and '042 Patents monitor the secondary containment of the submersibleturbine pump head and its riser pipe. The '661 Patent monitors thesecondary containment of internal dispenser fuel piping and a shearvalve coupled to the internal fuel dispenser piping. The presentapplication provides additional components and features that go beyondthe teachings of the aforementioned patents to provide certain featuresas improvements to such secondary containment monitoring systems.

There are several goals of the improved secondary containment monitoringand control system according to the present invention. One goal is toallow a common vacuum-generating source to generate a vacuum level tothe interstitial space of different fuel-handling components. A secondgoal is to detect if a product line's interstitial space contains ablockage such that a leak would go undetected if the leak existed on thedownstream side of the blockage. A third goal is to provide control toautomatically close the product line shear valves in response to a leakdetected in order to prevent fuel from further leaking in the event of ashear or loss of vacuum indicative of a leak in a fuel-handlingcomponent. A fourth goal is to provide a monitoring of an in-dispensersump having a secondary containment system and a redundant vacuum sourcegenerated for the in-dispenser sump in case one generation path containsa leak. There are additional goals and features provided as well.

Before addressing the particular aspects and features of the presentinvention, a typical fuel dispenser 10 is discussed and illustrated inFIGS. 1 and 2 as background information for discussion of the presentinvention. FIG. 3, discussed later below, starts the discussion of thenew features of the present invention.

FIG. 1 illustrates a fuel dispenser 10 that dispenses fuel to a vehicle.The fuel dispenser 10 is comprised of a housing 12. The housing 12supports or contains the fuel dispenser 10 components needed to receive,measure, and dispense fuel to a vehicle (not shown) as is well known. Ahose 14 and nozzle 16 are provided so that fuel carried internal to thefuel dispenser 10 is dispensed through the hose 14 and through thenozzle 16 into a vehicle fuel tank (not shown). The fuel dispenser 10contains a price display 18 that displays the price to be charged to thecustomer for fuel dispensed, and a volume display 20 that displays thevolume of fuel dispensed, typically in gallons or liters. The fueldispenser 10 may also contain an instruction display 22 that providesinformation, instructions, and/or advertising to the customerinterfacing with the fuel dispenser 10. Components inside the fueldispenser 10 are contained in the housing 12 accessible through acabinet door 23.

FIG. 2 contains an illustration of an internal view of some of thecomponents typically contained inside the fuel dispenser 10 as well assome fuel-handling components located beneath the fuel dispenser 10,typically underneath the ground. A fuel dispenser sump 24 may beprovided underneath the fuel dispenser 10 to capture any leaks that mayoccur in fuel piping that carries fuel to the fuel dispenser 10. Ifdouble-walled, the fuel dispenser sump 24 may be comprised of an outersump 25 surrounding an inner sump 26, which forms an interstitial space27 between the wall of the outer sump 25 and the inner sump 26. In thismanner, if a leak occurs in the inner sump 26, the outer sump 25 willcapture and contain the leak in the interstitial space 27.

The fuel is carried inside a main fuel piping 28 located underneath theground as illustrated. The fuel is typically pumped from a submersibleturbine pump (STP) located in the fuel storage tank (not shown) into themain fuel piping 28. The main fuel piping 28 typically enters into thefuel dispenser sump 24 via a sump pipe fitting 30. The main fuel piping28 is typically a double-walled fuel piping. The main fuel piping 32inside the fuel dispenser sump 24 is connected to the sump pipe fitting30 inside the sump 24 to carry the fuel onward. The main fuel piping 32located inside the dispenser sump 24 may be double-walled piping (innerwall not illustrated) as well to provide an extra measure of leakcontainment. The interstitial space of the main fuel piping 28 iscrimped onto the fuel dispenser sump 24 with the main fuel piping 32contained internal to the sump 24 being single-walled piping, and withthe fuel dispenser sump 24 providing the secondary containment.

The fuel is delivered to the individual fuel dispensers 10 via a branchfuel piping 36 that is coupled to the main fuel piping 32 typicallyusing a T-style fitting connection 34. As fuel is delivered to the fueldispenser 10 via the main fuel piping 28/32 and enters into the branchfuel piping 36, the fuel enters into fuel piping 40 internal to the fueldispenser 10 via a shear valve 38 that is coupled to the branch fuelpiping 36 and the internal dispenser fuel piping 40. As is well known,the shear valve 38 is designed to close the fuel flow path between thebranch fuel piping 36 and the internal dispenser fuel piping 40 in theevent of an impact to the fuel dispenser 10, which will in turn causethe shear valve 38 to shear in response thereto. An example of a shearvalve in the prior art is disclosed in U.S. Pat. No. 5,527,130, which ishereby incorporated herein by reference in its entirety.

After the fuel exits the outlet of the shear valve 38 and enters intothe dispenser fuel piping 40, it may encounter a flow control valve 42.The flow control valve 42 is under control of a control system 46 via aflow control valve signal line 48 inside the fuel dispenser 10. In thismanner, the control system 46 can control the opening and closing of theflow control valve 42 to either allow fuel to flow or not flow through ameter 56 and on to the hose 14 and nozzle 16. The control system 46typically instructs the flow control valve 42 to open when a fuelingtransaction is proper and allowed to be initiated.

The flow control valve 42 is contained below a vapor barrier 50 in ahydraulics area 52 of the fuel dispenser 10 where Class 1, Division 1components are provided for safety reasons and in an intrinsically safemanner, as described in U.S. Pat. No. 5,717,564, incorporated herein byreference in its entirety. The control system 46 is typically located inan electronics compartment 54 of the fuel dispenser 10 above the vaporbarrier 50 that does not have to be provided in an intrinsically safehousing. After the fuel exits the flow control valve 42, the fueltypically encounters the meter 56, wherein the fuel flows though themeter 56, and the meter 56 measures the volume and/or flow rate of thefuel. Typically, the meter 56 contains a pulser 58 that generates apulser signal 60 to the control system 46, indicative of the volumeand/or flow rate of fuel. In this manner, the control system 46 canupdate the price display 18 and the volume display 20, via a pricedisplay signal line 66 and a volume display signal line 64, so that thecustomer is informed of the price to be paid for the fuel as well as thevolume of fuel dispensed.

After the fuel exits the meter 56, the fuel is carried in additionaldispenser fuel flow piping 62, which is then coupled to a hose 14typically located in the upper housing or canopy of the fuel dispenser10 and on to the nozzle 16. The control system 46 of the fuel dispenser10 may be coupled to an external site controller 68 via a fuel dispensercommunication network 70. The site controller 68 may be the G-Site® orPasspor® point-of-sale (POS) system, both manufactured by Gilbarco Inc.for example. The site controller 68 communicates with the control system46 to authorize and control the fuel dispenser 10 activation as well ascommunications for payment handing for payment media presented at thefuel dispenser 10, among other things.

Overview of Secondary Containment Monitoring and Control System

As previously discussed, the present invention is a secondarycontainment monitoring and control system that detects leaks andprovides controls to control fuel flow to prevent additional leaks. Thecontrol involves a vacuum actuated shear valve. A vacuum-generatingsource generates a vacuum in a monitored space. If a loss of vacuumoccurs, the vacuum actuated shear valve automatically closes to cut offfuel flow to prevent fuel from being further supplied to the leak. Anexemplary secondarily contained fuel delivery monitoring and controlsystem for the service station is described below. The variouscomponents, systems and operations to achieve the aforementioned goalsare described in the context of various parts of the monitoring andcontrol system.

FIG. 3 illustrates an overall secondary containment system forcontaining and monitoring leaks that occur in fuel-handling componentsin a service station environment in accordance with the presentinvention. A description of the travel path of the fuel to the fueldispenser as it travels through the fuel-handling components is nowdescribed. As illustrated, a fuel dispenser 10 is disclosed thatdelivers fuel to a customer's vehicle from a storage tank 72. Thestorage tank 72 is typically located beneath the ground, and is alsocommonly referred to as an “underground storage tank” (UST). The storagetank 72 is comprised of an inner container 74 surrounded by an outercontainer 76. An interstitial space 78 is formed between the inner andouter containers 74, 76. In this manner, if a breach occurs to the innercontainer 74, fuel 80 stored inside the inner container 74 will leak andbe captured inside the interstitial space 78 by the outer container 76and prevented from leaking to the ground if no leak exists in the outercontainer 76.

In order to detect a leak or breach in either the inner or outercontainers 74, 76, the interstitial space 78 is monitored to determineif a leak exists. A liquid solution, such as brine for example, may alsobe placed in the interstitial space 78 be used for leak detection.Alternatively, the interstitial space 78 may be placed under a vacuum orpressure by a vacuum-generating source, like the system disclosed in the'534 Patent, previously referenced. The vacuum-generating source may beprovided from a siphon port 87 on a submersible turbine pump 82 asillustrated in FIG. 3 disclosed in the '534 Patent, or from a separatevacuum-generating source 372 and pressure sensor 370 combinationprovided separately and externally form the submersible turbine pump 82.In the system of the '534 Patent, the system monitors pressurevariations in the interstitial space 78 in order to detects leaks thatoccur in both the inner and outer containers 74, 76 of the storage tank72. In this manner, if a leak occurs in the outer container 76, thesystem serves as a leak prevention system, since a leak of fuel 80 tothe environment will not actually occur unless there is a leak in theinner container 74 as well.

In order to draw fuel 80 out of the storage tank 72 for delivery to thefuel dispensers 10, the submersible turbine pump 82 is typicallyprovided. The submersible turbine pump 82 is comprise of a head 84containing power and control electronics (not shown) that provide powerthrough a riser pipe 86 down to a boom 88 inside the storage tank 72eventually reaching a turbine pump (not shown) contained inside an outerturbine pump housing 90. As power is applied by the electronics to causethe turbine rotor to rotate, a pressure differential is caused betweenthe turbine motor housing (not shown) and the outer housing 90 to drawfuel 80 upward from the storage tank 72 into the boom 88 and riser pipe86 for delivery to the fuel dispensers 10. The submersible turbine pump82 may contain a siphon 81 that allows the submersible turbine pump 82to generate a vacuum using the force of fuel 80 to flow as described inthe '534 Patent. More information on a submersible turbine pumpproviding a siphon may be found in U.S. Pat. Nos. 6,622,757,incorporated herein by reference in its entirety.

The riser pipe 86 may be secondarily contained with a surrounding outerpiping 94, as illustrated in FIG. 3, to provide containment of leaksthat may occur in the riser pipe 86. An interstitial space 95 is formedby the space between the riser pipe 86 and the surrounding outer piping94. In this manner, much like the storage tank outer container 76 andinterstitial space 78, the interstitial space 95 can be monitored forleaks. One method of monitoring for leaks is by generating a vacuum inthe interstitial space 95 using a vacuum-generating source, like thatdescribed in U.S. Pat. No. 6,997,042 (the “'042 Patent”), previouslyreferenced. By generating a vacuum level in the interstitial space 95and monitoring pressure in the interstitial space 95, a breach of eitherthe riser pipe 86 or the surrounding outer piping 94 may be detectedsince a pressure variation will occur if either is breached. Thevacuum-generating source may be provided from the siphon port 87 on thesubmersible turbine pump 82, or from a separate source.

It may also be desirable to secondarily contain the submersible turbinepump head 84 to capture and monitor leaks that may occur from the head84. U.S. Pat. No. 7,010,961 (the “'961 Patent”), previously referenced,discloses such a system. The head 84 is placed inside and surrounded byan enclosure or head container 96. An interstitial space 97 is formedbetween the head 84 and the head container 96. The head container 96must contain an orifice that is sealed, but adapted to receive the riserpipe 86 and its surrounding outer piping 94 as well as a main fuelpiping 106. If a leak occurs in the submersible turbine pump head 84,the leak will be captured inside and at the bottom of the head container96. If monitoring of leaks is desired, a vacuum-generating source isprovided to generate a vacuum or pressure in the interstitial space 97.Pressure variations are then monitored to determine if there is a breachin the head 84 or the head container 96.

The submersible turbine pump 82 and head container 96, if provided, aretypically placed inside a submersible turbine pump sump 98. The STP sump98 serves as a holding container for the submersible turbine pump 82under the ground and to mount the submersible turbine pump 82 on top ofthe fuel storage tank 72. The STP sump 98 contains an access port 100 sothat service personnel can reach and gain access to the submersibleturbine pump 82 for repairs or maintenance.

Although FIG. 3 illustrates one fuel storage tank 72 and submersibleturbine pump 82 combination, it is understood that each grade of fuelprovided at the service station will be contained in additional fuelstorage tanks 72 and pumped out using submersible turbine pump 82combinations. Further, two or more submersible turbine pumps 82 may besiphoned together as disclosed in U.S. Pat. No. 5,544,518, incorporatedherein by reference in its entirety.

After the fuel 80 is drawn by the submersible turbine pump 82 into thehead 84, the fuel is carried through orifices 102 and 104 through theSTP sump 98 and the head container 96 to a main fuel piping 106 thatcarries fuel 80 to the fuel dispensers 10 for eventual delivery. Themain fuel piping 106 is a double-walled piping comprised of a main innerpiping 108 that carries the fuel 80, surrounded by a main outer fuelpiping 110 that provides secondary containment of a main inner fuelpiping 108. The secondary containment is provided since the main fuelpiping 106 is a fuel-handling component. A main fuel piping interstitialspace 111 is formed between the main inner fuel piping 108 and the mainouter fuel piping 110. Any fuel 80 that leaks from the main inner fuelpiping 108 will be captured by the main outer fuel piping 110 and restinside the main fuel piping interstitial space 111 if the main outerfuel piping 110 does not contain a leak. Thus, the main fuel pipinginterstitial space 111 is monitored to detect leaks in both the maininner and outer fuel pipings 108, 110. A vacuum-generating source, suchas the submersible turbine pump 82 using its siphon 87, or standalonevacuum-generating source may be used to generate a vacuum or pressure inthe main fuel piping interstitial space 111. Pressure variations in themain fuel piping interstitial space 111 are monitored to detect a breachin either the main inner fuel piping 108 or the main outer fuel piping110. Such as system is disclosed in U.S. Patent Application PublicationNos. US 2004/0045343 A1; U.S. 2005/0039518 A1; US 2005/0145016 A1; andUS 2005/024711 A1, previously referenced.

The fuel 80 is carried inside the main inner fuel piping 108 and throughthe below ground fuel dispenser sump 24 via a sump orifice 112 until itreaches branch fuel piping 114. The branch fuel piping 114 is fuelpiping dedicated to an individual fuel dispenser 10 that is coupled tothe main fuel piping 106 to tap into the main fuel supply 80 carried bythe main fuel piping 106. The branch fuel piping 114 is a double-walledfuel piping comprised of an inner and outer piping similar to that ofthe main fuel piping 106 such that the branch fuel piping 114 issecondarily contained for capture and monitor of leaks as describedabove. A branch fuel piping 114 is provided for each grade of fueldelivered by the fuel dispenser 10. In the example illustrated in FIG.3, the fuel dispenser 10 is a blending fuel dispenser. Only the high andlow grades of gasoline are supplied to the fuel dispenser 10. The fueldispenser 10 blends the two grades of gasoline to provide intermediategrades of fuel.

The branch fuel piping 114 carries the two grades of fuel intoindependent product line shear valves 116, typically provided at thebase of the fuel dispenser 10. The product line shear valves 116contains an internal flow path to carry the fuel 80 from the branch fuelpiping 114 to internal dispenser fuel piping 118 on its way to beingdispensed through the hose 14 and nozzle 16. The product line shearvalves 116 are designed to shear and close off the fuel flow path of theinternal fuel dispenser piping 118 in the event of an impact to the fueldispenser 10. The shear valve 116 typically contains one or more poppetvalves (not shown) that are designed to close when a shear occurs as isdescribed in U.S. Pat. No. 5,527,130, previously referenced.

In the present invention, the product line shear valves 116 aredouble-walled shear valves that provide secondary containment. Theproduct line shear valve 116 contains an internal fuel flow path formedby an inner housing (not shown), surrounded by an outer housing, therebyforming an interstitial space (not shown) therebetween. In this manner,a fuel 80 leak that occurs in the inner housing is captured andcontained in the outer housing similar to the other aforementionedsecondarily contained fuel-handling components. An example of adouble-walled shear valve 116 that may be used with the presentinvention is described in the '390, '394, and '886 Applications,previously referenced.

The product line shear valves 116 are designed for their interstitialspace to couple to the interstitial space of the branch fuel piping 114when the two are coupled together so that both spaces can be drawn undera vacuum and monitored as one space or “zone.” Further, the internaldispenser fuel piping 118 may be a double-walled fuel piping comprisedof an inner dispenser fuel piping 120 surrounded by an outer dispenserfuel piping 122. A dispenser fuel piping interstitial space 123 isformed between the inner dispenser fuel piping 120 and the outerdispenser fuel piping 122. The interstitial space of the shear valve 116and/or the branch fuel piping 114 may be fluidly coupled to a dispenserfuel piping interstitial space 123 so that all three interstitial spacesmay be monitored as one zone and so that leaks from all threefuel-handling components are collected together. If the main fuel pipinginterstitial space 111 is fluidly coupled to the branch fuel pipinginterstitial space, leaks that are captured in either the internal fueldispenser piping 118, the product line shear valve 116, and/or thebranch fuel piping 114 may be captured and returned to the storage tank72 via the main fuel piping interstitial space 111 if coupled to thestorage tank 72. Further, leaks captured by the head container 96 andthe surrounding outer piping 94 of the riser pipe 86 may be returned tothe storage tank 74 as well. Such a system is described in the '157Application and the '161, '269, and '054 Patents, previously referenced.In this manner, separate evacuation of the interstitial spaces may notbe necessary to save service costs.

After the fuel 80 travels into the fuel dispenser piping interstitialspace 123, the fuel eventually reaches a portion of internal fueldispenser piping 124 coupled to the double-walled internal dispenserfuel piping 118 that is not secondarily contained (i.e. does not containan outer piping). The internal fuel dispenser piping 124 may becontained above the fuel dispenser sump 360 (illustrated in FIG. 11)such that leaks from the internal fuel dispenser piping 124 are capturedby the dispenser sump 360 thereby alleviating the need for the internalfuel dispenser piping 124 to need secondary containment. The fuel 80then travels through a fuel filter coupling 126 coupled inline to thedispenser piping 124 and through a fuel filter 128 attached to a fuelfilter coupling 126. In this manner, the fuel 80 will travel through thefuel filter 128 to filter out contaminants before reaching the hose 14and nozzle 16. An example of a fuel filter coupling 126 and fuel filter128 combination is disclosed in U.S. Pat, No. 5,013,434, incorporatedherein by reference in its entirety.

After the fuel 80 leaves the fuel filter 128, the individual internalfuel dispenser pipings 124 are manifolded together for either the high,low, or-blended grade of fuel 80 to be dispensed through a single hose14. The fuel dispenser 10 illustrated in FIG. 3 is a single hosedispenser 10, but could also be a multi-hose dispenser 10 as well. Thefuel dispenser 10 illustrated in FIG. 3 is also a vapor-recoveryequipped dispenser that recovers vapors through the nozzle 16 and hose14 to return to the storage tank 72. An example of a vapor-recoveryassist equipped fuel dispenser is disclosed in U.S. Pat. No. 5,042,577,incorporated herein by reference in its entirety. The fuel dispenser 10contains internal vapor return piping 130 coupled to a vapor flow meter132 that measures vapor collected by the nozzle 16 when fuel 80 isdispensed. The vapor flow meter 132 may be used for in-stationdiagnostics (ISD) and monitoring or control of vapor recovery, asdisclosed in U.S. Pat. No. 6,622,757, incorporated herein by referencein its entirety.

After the recovered vapor passes through the vapor flow meter 132, thevapor then passes through an internal vapor return piping 134 internalto the fuel dispenser 10 on the outlet side of a vapor line shear valve117 on its way to being sent back to the storage tank 72. The internalvapor return piping 134 is comprised of an internal inner vapor returnpiping 136 surrounded by an internal outer vapor return piping 138. Aninterstitial space 139 is formed between the internal inner and internalouter vapor return piping 136, 138. In this manner, secondarycontainment is provided for the internal vapor return piping 134 as wellin case the internal inner vapor return piping 136 contains a leak.Because the vapor line shear valve 117 is also a double-walled shearvalve, the internal vapor piping interstitial space 139 is coupled to aninterstitial space (not shown) of the vapor line shear valve 117 and isreturned to vapor return piping 140 located on the inlet side of thevapor line shear valve 117, typically inside the fuel dispenser sump 24.The vapor return piping 140 is comprised of an inner vapor return piping142 surrounded by an outer vapor return piping 144. A vapor returnpiping interstitial space 145 is formed between the inner and outervapor return piping 142, 144. The vapor return piping 140 is coupled tothe storage tank 72 via coupling 148. More specifically, the inner vaporreturn piping 142 is fluidly coupled to the ullage 150 of the storagetank 72 where vapors reside. In this manner, the recovered vapor isrecombined with the vapor in the ullage 150 to prevent vapor emissionsto atmosphere. The vapors recombine and liquify into fuel 80.

If the pressure in the storage tank 72 becomes too high or too low, avent allows the vapor/air mixture in the ullage 150 to either be ventedto atmosphere or air to be drawn into the ullage 150 to stabilize thepressure. A vent coupling 152 is provided that is fluidly coupled to theullage 150 of the storage tank 72. The vent coupling 152 is attached toa vent pipe 153, which may be comprised of an inner vent piping 154surrounded by an outer vent piping 156. In this manner, any leak in theinner vent piping 154 contains the vapors in the ullage 150 in a ventpiping interstitial space 157 formed between the inner and outer ventpiping 154, 156.

As the vapor from the ullage 150 travels through the inner vent piping154, the vapor will travel through an above ground vent piping 158 thatis coupled to a pressure-relief (P/V) valve 160. The P/V valve 160 isdesigned to open when extreme pressure conditions occur in the ullage150 so that air is either ingested or vapor in the ullage 150 exhaustedto atmosphere to prevent the pressure in the ullage 150 from stabilizingat extreme pressure ranges.

Several control systems are provided in the service station illustratedin FIG. 3. The site controller 68 and a tank monitor 168 are coupled tothe fuel dispenser communication network 70. The tank monitor 168provides tank reconciliation by receiving information about metered fuel80 dispensed from the fuel dispensers 10 or site controller 68 and fromtank level probes (not shown) in the storage tank 72. The fuel dispenser10 of the present invention contains a dispenser sensor module (DSM) 170that communicates with and controls certain aspects of secondarycontainment monitoring and control according to the present invention.The DSM 170 will be described in more detail below in this applicationstarting with FIG. 11. The DSM 170 is communicatively coupled to thefuel dispenser communication network 70 to communicate with the tankmonitor 168 as will be later described as well.

Overview of Monitoring and Control Components

Now that the overall system and fuel-handling components for fuel 80transport from the storage tank 72 to the fuel dispensers and secondarycontainment has been described, novel fuel handing, monitoring, andcontrol components of the present invention will now be described.

FIGS. 4-12 described below set forth various components and features ofthe secondary containment monitoring and control system. FIGS. 13-20describe an embodiment of the present invention employing the componentsand features described in FIGS. 4-12.

Vacuum-Actuated Shear Valve

One stated goal of the present invention is to provide automatic controland closing of the product line shear valves 116 in the event that aleak is detected. In this manner, fuel 80 is not continuously suppliedto the leak source if the leak exists in a fuel-handling componentlocated in the fuel flow path on the output of the product line shearvalve 116. In order to accomplish this goal, the present inventionprovides for the product line shear valves 116 to be “vacuum actuated.”A vacuum-actuated shear valve is shear valve that automatically closesits internal fuel flow path when there is a sufficient loss of vacuumbecause a leak is detected due to a loss of vacuum as a result ofdrawing a vacuum in the interstitial space of fuel-handling components.In the present invention, providing a vacuum-actuated shear valve thatis coupled to the interstitial space provides a convenient way toautomatically close the product line shear valve in response to a leak(i.e. loss of vacuum).

FIG. 4 illustrates one embodiment of a vacuum-actuated product lineshear valve 116 in accordance with the present invention that isdesigned to close the fuel flow path internal to the product line shearvalve 116 in response to a loss of vacuum. The loss of vacuum may becaused by a leak. The product line shear valve 116 illustrated in FIG. 4is a double-walled shear valve like those described in the '390, '394,and '886 Applications, previously referenced. As previously discussedabove, an interstitial space of fuel-handling components may be drawnunder a vacuum level, wherein a vacuum monitoring system monitors thevacuum level of the interstitial space to detect a breach or leak, likethe systems described in the '343, '518, '016, and '111 Applications,and the '534, '042, '961, '660, and '661 Patents, previously referenced.

Note that although the shear valve illustrated in FIG. 4 can be used aseither a product line shear valve 116 or a vapor line shear valve 117,only the product line shear valve 116 contains the vacuum actuator inthe disclosed embodiment. This is because it is only desired to closethe product line shear valve 116 in response to a leak. The vapor lineshear valve 117 does not close, because the vapor return piping 140 is acommon piping for all internal fuel dispenser piping product lines 118within the fuel dispenser 10 to return vapors of FIG. 3. If a leak wereto exist in a particular product main fuel piping 106 or internal fueldispenser piping 118, 124 such that a product line shear valve 116 isclosed as a result, thus shutting down delivery of that product line,the vapor return piping 106 cannot be closed since it services otherproducts fuel pipings 106. However, the vapor line shear valve 117 couldbe designed to actuate and close automatically in response to a leak(i.e. loss of vacuum) just like the product line shear valve 116 ifdesired. The product line shear valve 116 and the vapor line shear valve117 can be comprised of the same construction and components so thatboth shear valves 116, 117 are double-walled to provide secondarycontainment of leaks.

The product line shear valve 116 illustrated in FIG. 4 is adouble-walled shear valve like those described in the '390, '394, and'886 Applications, previously referenced. The discussion below isapplicable to both the product line shear valve 116, or the vapor lineshear valve 117, although only the product line shear valve 116 containsthe vacuum actuator. As illustrated in FIG. 4, the shear valves 116, 117accept the double-walled piping 106, 140 that is comprised of the outerpiping 110, 144 surrounding the inner piping 108, 142 with theinterstitial space 111, 145 formed therebetween, as previously describedin FIG. 3. Fuel or vapor flows in the inner piping 108, 142 into theshear valves 116, 117. As discussed in the '390, '394, and '886Applications, the double-walled piping 106, 140 is coupled to anupstream housing 162 that is attached to a containment housing 164 and adownstream housing 166. The upstream, containment, and downstreamhousings 162, 164, 166 fit together to provide an internal fuel flowpath as well as a containment housing forming an interstitial spacetherebetween as disclosed in the '390, '394, and '886 Applications.Providing a double-walled shear valve 116, 117 allows the interstitialspace 111, 145 of the piping 106, 140 and the shear valve 116, 117 to becoupled together on the upstream side of the shear valve 116, 117 andmonitored for leaks as one space or zone using a singlevacuum-generating source to generate a vacuum level in the interstitialspace 111, 145, as discussed in the '504 Application, previouslyreferenced.

On the downstream side of the shear valve 116, 117, an internal fueldispenser piping 118, 134 that either carries fuel or vapor is coupledto the downstream housing 166 of the shear valve 116, 117 to carry thefuel 80 or vapor to and from the hose 14 and nozzle 16 of the fueldispenser 10. In the illustrated embodiment, the internal dispenserpiping 118, 134 is doubled-walled piping comprised of the inner piping120, 136 surrounded by the outer piping 122, 138 as previouslydescribed, wherein the interstitial space 123, 139 is coupled to theinterstitial space of the shear valve 116, 117 (not shown), which iscoupled in turn to the branch piping interstitial spaces 111, 145. Allof these interstitial spaces are coupled together for leak monitoring asdescribed in '504 Application, previously referenced.

The shear valve 116, 117 is illustrated as having a latch 178 having anarm 180 secured through the housing of the shear valve 116, 117 to amain poppet valve (not shown) contained internal to the shear valve 116,1117 as described in the '390, '394, and '886 Applications, previouslyreferenced. The arm 180 is spring biased downward, but is held upward byits connection to a fusible link 188 via connection 184. If the fusiblelink 188 is released, the energy stored in the spring (not shown) isreleased causing the arm 180 to move downward, thereby closing the mainpoppet valve contained internal to the shear valve 116, 117. This closesoff the flow path inside the shear valve 116, 117 to prevent fuel 80flow. The fusible link 188 is designed to fail, thereby allowing the arm180 to move downward and close the flow path inside the shear valve 116,117 if an extreme temperature surrounds the fusible link 188, such asdue to a fire.

The fusible link 188 is also connected to a vacuum-actuated solenoid 186in the case of the product line shear valve 116. The vacuum-actuatedsolenoid 186 in its deactivated state applies a pulling force on thefusible link 188 to thereby apply a pulling force on the arm 180 to keepthe flow path internal to the product line shear valve 116 open. Thevacuum actuated solenoid 186 is coupled to a vacuum conduit or tubing176 via a fitting 190, which is in turn connected to an interstitialspace fitting 174 on the external body of the product line shear valve116. The interstitial space fitting 174 couples the vacuum conduit 176to the interstitial space internal to the product line shear valve 116.As illustrated in FIG. 4, the branch piping interstitial space 111, theinterstitial space of the product line shear valve 116, and the internalfuel dispenser piping interstitial space 123 are all fluidly coupledtogether. Thus, coupling the vacuum conduit 176 to the interstitialspace fitting 174 couples the vacuum conduit 176 and vacuum actuator 186to these interstitial spaces 111, 123 for monitoring of leaks.

If a leak occurs in any of the interstitial spaces 111, 145, 123, 139,such that a change in pressure or vacuum level were to occur likedescribed in the vacuum monitoring system of the '504 Application, thisloss of vacuum causes the vacuum actuated solenoid 186 to release thefusible link 188, which would in turn cause the arm 180 to move downwardand close the main poppet valve of the product line shear valve 116.This causes the flow path internal to the product line shear valve 116to be closed, thereby cutting off the source of fuel 80 or vapor fromcontinuing to be delivered to the leak. The vacuum monitoring system canthen generate an appropriate alarm or signal to alert service personnelof the leak.

The internal fuel dispenser piping 118, 134 illustrated in FIG. 4 alsocontains an interstitial space port 192 that allows the interstitialspace 123, 139 to be coupled via tubing 194 to another system. Thisallows the interstitial space 123, 139 to be coupled to anotherinterstitial space containing another fuel-handling component to allowsuch component to be monitored in the same zone. A loss of vacuumgenerated as a result of a leak in this other interstitial space canthen also control the vacuum actuated solenoid 186 to close the flowpath of the product line shear valve 116 in the event of a leak.

FIG. 5 illustrates the product line shear valve 116 in accordance withanother embodiment of the present invention similar to the embodiment inFIG. 4. Instead of the vacuum actuated solenoid 186, via the vacuumtubing 176, being coupled to an interstitial space fitting 174 on theproduct line shear valve 116, the vacuum conduit 176 is coupled to aninterstitial space fitting 196 on the internal fuel dispenser piping118, 134. This may be advantageous over providing the interstitial spacefitting as part of the product line shear valve 116 for various reasons,or if the interstitial space 123, 139 of the internal fuel dispenserpiping 118, 134 is not coupled to the interstitial space of the shearvalves 116, 117 and/or the branch piping 111, 145. If a separatevacuum-generating source is used to draw a vacuum in the interstitialspace 123, 139 of the internal dispenser piping 118, 134 separate fromthe interstitial space of the shear valve 116 and/or branch pipinginterstitial spaces 111, 145, and it is desired for the product lineshear valve 116 to close due to a loss of vacuum in the internal fueldispenser piping 118, 134, it is necessary to couple the vacuum actuatedsolenoid 186 directly to the internal dispenser piping interstitialspaces 123, 139.

FIG. 6 illustrates a third embodiment of a double-walled shear valve116, 117 that is disclosed in the '394 and '886 Applications, previouslyreferenced. The shear valve 116, 117 may be used for either the productline internal fuel dispenser piping 118 or the internal vapor returnpiping 186. But, for the product line version of the product line shearvalve 116, it is fitted with the vacuum actuator 186. The vacuumactuator 186 is coupled to the interstitial space of the shear valve 116as illustrated in FIG. 12 of the '394 and '886 Applications. The vacuumactuator 186 is designed to apply a rotational force to a rotatableshaft 182 to open and close a main poppet valve (not shown) inside theproduct line shear valve 116 that controls the opening and closing ofthe flow path in response to generation or loss of a vacuum level in theinterstitial space. As discussed previously, the interstitial space ofthe shear valve 116 may be coupled to the interstitial space of theinternal fuel dispenser piping interstitial space 123, or the branchfuel piping interstitial space 111. In this manner, a loss of vacuum ineither of these two interstitial spaces will cause the vacuum actuator186 to close the main poppet valve of the product line shear valve 116,thereby closing the flow path.

The vacuum actuator 186 is comprised of an internal vacuum actuationdevice (not shown) that retracts a vacuum actuator shaft 210 from avacuum actuator orifice 220 in response to generation of a sufficientvacuum level. The vacuum actuator 186 is attached to the containmenthousing 164 of the product line shear valve 116 via a vacuum actuatormounting plate 212. The vacuum actuator mounting plate 212 contains twomounting orifices 213. A mounting bolt 214 is placed inside one mountingorifice 213 to secure the plate 212 to the containment housing 164. Therotatable shaft 182 that protrudes the containment housing 164 fitsinside the other orifice 213 and is secured using another bolt 206.

The vacuum actuator shaft 210 is coupled to an attachment means 218 thatis attached to a lever 208 attached to the rotatable shaft 182. Therotatable shaft 182 is spring biased in a clockwise rotationaldirection. When a sufficient vacuum level is generated, the vacuumactuator 186 pulls the vacuum actuator shaft 210 inward, thereby causingthe rotatable shaft 182 to rotate counter-clockwise. This opens the mainpoppet valve inside the flow path within the product line shear valve116 to allow fuel 80 to flow. When the vacuum level is sufficiently lostin the interstitial space coupled to the vacuum actuator 186, the vacuumactuator 186 moves the vacuum actuator shaft 210 outward therebyreleasing the energy in the spring biased rotatable shaft 182, causingit to rotate clockwise. This closes the main poppet valve inside theflow path of the product line shear valve 116, thereby cutting off fuel80 flow. This is because a loss of vacuum level in the interstitialspace coupled to the vacuum actuator 186 is indicative of a leak orother condition where it is desired to close the product line shearvalve 116.

The shear valve 116, 117 may be used as both a product line or vaporline shear valve, but only the product line shear valve 116 contains thevacuum actuator 186 in the preferred embodiment. The double-walled shearvalve 116, 117 illustrated in FIG. 6 is attached to the branch piping106, 140 as well as the internal dispenser piping 122, 138. The branchpiping 106, 140 may include a flex connection piping portion 221 toallow flexibility when attaching the branch piping 106, 140 to thedouble-walled shear valve 116, 117 in the field. Vapor and fuel 80 flowfrom the storage tank 72 travels through internal dispenser piping 122,138 and the double-walled shear valve 116, 117 when the main poppetvalve inside the shear valve 116, 117 is opened. The internal dispenserpiping 122, 138 is attached to the upstream housing 162 of thedouble-walled shear valve 116, 117 via fasteners 222. The branch fuelpiping 106, 140 is attached to the upstream housing 162 of the shearvalve 116, 117 via fasteners 200 that are fitted into orifices 205 andsecured tightly via bolts 202.

Shear Valve Actuation

At this point, a product line shear valve 116 has been discussed that isdesigned to close due to a loss of vacuum in a space coupled to thevacuum conduit 176. FIG. 7 illustrates a system and method ofautomatically closing the flow path of the product line shear valve 116in response to other conditions as well where automatic closing of theproduct line shear valve 116 is desired. These other conditions includedetection of a leak collected at the bottom of the fuel dispenser sump24, selecting a service setting, and/or the closing of a filterinterlock to change the filter 128 in the fuel dispenser 10 in order toprovide an automatic safety mechanism when changing the filter 128.

As illustrated in FIG. 7, the double-walled product line shear valve 116is shown as receiving the branch piping 106, 140 that runs into andinside the fuel dispenser sump 24 as illustrated previously in FIG. 3.The product line shear valve 116 contains the vacuum controlled solenoid186, like that illustrated in FIGS. 4-6, such that the product lineshear valve 116 will close in response to a loss of vacuum in the vacuumconduit 176 coupled to an interstitial space drawn under a vacuum, aspreviously described. The product line shear valve 116 is typicallymounted to a mounting rod (not shown) located above the fuel dispensersump 24, wherein the mounting rod is connected to the mounting bosses170, 172 of the product line shear valve 116. The mounting rod istypically located at the top of the fuel dispenser sump 24 or in closeproximity.

Dispenser Sump Leak Detector/Float Switch

Another aspect of the present invention is to provide a system andmethod wherein the product line shear valve 116 automatically closes itsflow path in response to a leak in the fuel dispenser sump 24 inaddition to the internal fuel dispenser piping 118. This is because aleak detected in the fuel dispenser sump 24 is a result of a leak of afuel-handling component. In order to provide this feature, the dispensersump 24 is designed to trigger a loss of vacuum at the vacuum actuatedsolenoid 186 of the product line shear valve 116 as follows.

As illustrated in FIG. 7, a float 234 is provided in the bottom of thefuel dispenser sump 24 to detect leaks. Any leaks that occur in the mainfuel piping 106 will collect at the bottom of the fuel dispenser sump 24due to gravity. As the volume of the leak increases in the bottom of thefuel dispenser sump 24, the leak will cause the float 234 to rise. Asthe float 234 rises, the float 234 will push upward on a shaft 236 thatis coupled to the float 234 and is also coupled to a float valve 238that acts as a switch. The float valve 238 is coupled to theinterstitial space that is coupled to the vacuum conduit 176 via aconduit 250 via connector 246, described in more detail below. As theshaft 236 is raised by the float 234 as the result of a captured leak,the shaft 236 will cause the float valve 238 to open a vent 240 toatmosphere thereby allowing air into the conduit 250 coupled to thefloat valve 238 and introducing a loss in vacuum in the conduit 250 andeventually the vacuum conduit 176. Because the vacuum conduit 176 iscoupled to the vacuum actuator 186, the loss of vacuum willautomatically cause the product line shear valve 116 to close.

Optionally, the conduit 250 may also be coupled to an interstitial space232 of the fuel dispenser sump 24 via an interstitial space fitting 242and conduit 244. A vacuum-generating source (not shown) that generates avacuum in the interstitial space 27 of the fuel dispenser sump 24creates a vacuum in the conduit 244, that is coupled to the conduit 250via float valve 238, and eventually the vacuum conduit 176 connected tothe vacuum actuator 186. Note that although the shear valve 116illustrated in FIG. 7 resembles the shear valve embodiments of FIGS.4-5, shear valve 116, 117 illustrated in FIG. 6 may also be employedwith its vacuum actuator 186. Note that the vacuum conduit 176 can beconnected to other interstitial spaces, including those illustrated inFIGS. 4-6. In this manner, a loss of vacuum due to a leak in the fueldispenser sump interstitial space 27 will also cause a loss of vacuum totrigger the closing of the shear valve 116, 117 as well.

The flowchart in FIG. 8 illustrates the process whereby the product lineshear valve 116 automatically closes in response to a leak in the fueldispenser sump 24. The process starts (block 300), and the serviceswitch 248 is set to the “RUN” setting 256 (block 302). Thereafter, avacuum is drawn inside the vacuum conduit 176 using a vacuum-generatingsource (block 304). The vacuum conduit 176 may be connected to theinterstitial space of one or more fuel-handling components as previouslydescribed above. The vacuum-generating source continues to draw a vacuumin the vacuum conduit 176 until it a sufficient vacuum level is presentto actuate the vacuum actuator 186 (decision 306). The vacuum actuator186 is designed to respond to a vacuum level that is also sufficient tobe indicative of the lack of a leak in a fuel-handling component'sinterstitial space coupled to the vacuum actuator 186. Once the vacuumlevel is sufficient in the vacuum conduit 176 (decision 306), the vacuumactuator 186 applies a pulling force on the latch 178 of the shear valve116, 1117 to open the main poppet valve inside the flow path of theproduct line shear valve 116, 117 and to keep it open (block 308).

Thereafter, the system remains operational and the product line shearvalve 116 open until a loss of vacuum occurs. The loss of vacuum mayoccur due to a leak in interstitial space coupled to the vacuum actuator186 or a leak in the fuel dispenser sump 24 If there is a leak in thefuel dispenser sump 24, the float 234 will rise and eventually cause thevent 240 to open, thereby allowing air into the vacuum conduit 176 thatis coupled to the vacuum actuator 186 (decision 310). Once a vacuum lossoccurs, the vacuum actuator 186 causes the flow path of the shear valve116, 117 to close (block 312). A communication line 243 is coupledbetween the float valve 238 and the tank monitor 168 so that an openingof vent 240 causes a signal to be sent to the tank monitor 168 to informthe tank monitor 168 that a leak has occurred in the fuel dispenser sump24 (block 314). The tank monitor 168 can generate the appropriatenotification or alarm to alert service personnel either on-site orremotely (block 316). The tank monitor 168 may, in response to the leak,cause the submersible turbine pump 82 to shut down so that fuel 80 doesnot continue to be supplied to the leak (block 318). Thereafter, theprocess ends (block 320).

Service Switch

Another aspect of the present invention takes advantage of thevacuum-actuated shear valve 116 to divert the shear valve 116 toautomatically close in response to a servicing of the fuel dispenser 10by service personnel as a safety precaution. In this manner, the mainfuel pipings 106 are depressurized automatically without servicepersonnel having to manually close the product line shear valves 116when servicing fuel-handling components.

The system is designed so that when a loss of vacuum occurs in theconduit 244, a loss of vacuum also occurs in the conduit 250 coupled toa service switch 248 that controls the operation of the system of thepresent invention. The service switch 248 has a lever 254 that controlsthe operation of the service switch 248. When the service switch lever254 is set to the “RUN” position 256, the conduit 250 and the conduit264 are coupled to each other so that a loss of vacuum that occurs inthe conduit 250 is communicated to conduit 264. Since conduit 264 iscoupled to the vacuum conduit 176 of the vacuum actuator 186 on theproduct line shear valve 116, any loss of vacuum in the conduit 264 willcause the product line shear valve 116 to close as previously discussed.

The service switch 248 also has a “SERVICE” setting 258 that servicepersonnel can switch the lever 254 to for servicing the fuel dispenser10. When service personnel services the fuel dispenser 10, they aresupposed to manually release the latch 178 from the fusible link 188 toclose the product line shear valve 116 so that the fuel-handlingcomponents and piping inside the fuel dispenser 10 are depressurized forsafety reasons. However, this safety feature relies on manualintervention by service personnel that if not remembered and taken, canintroduce human error that can lead to pressurized fuel 80 spilling ontoservice personnel when servicing the fuel dispenser 10. When the serviceis complete, the service personnel is supposed to reset the latch 178 onthe product line shear valve 116 to again connect it to the fusible link188 to open the product line shear valve 116 for normal operation.Therefore, since the present invention provides a method ofautomatically closing the product line shear valve 116 due to a loss ofvacuum, the service switch 248 can be designed so that the lever 254being set to the “SERVICE” setting 258 causes a loss of vacuum in theconduit 264 that is coupled to the vacuum conduit 176 and the vacuumactuator 186. In this manner, the product line shear valve 116 willautomatically close when the fuel dispenser 10 is being serviced afterthe “SERVICE” setting 258 is selected.

In this regard, the service switch 248 contains a vent 252 that opens toallow air in when the lever 254 is switched to the “SERVICE” setting258. This in turn causes air to come into the service switch 258 andinto the conduit 264, which causes a loss of vacuum in the vacuumconduit 176 and actuates the vacuum actuator 186 to close the productline shear valve 116. When the service switch 248 is set back to the“RUN” setting 258, thereby closing vent 252, and when a sufficientvacuum level is applied to the vacuum conduit 176 via avacuum-generating source, the vacuum level will cause the vacuumactuator 186 to automatically open the flow path of the product lineshear valve 116. Thus, when a service person is finished servicing thedispenser, service personnel do not have to reset the product line shearvalve 116. The product line shear valve 116 automatically resets to theopen position when a sufficient vacuum level is once again established(i.e. no leak).

In the flowchart of FIG. 9, the process is illustrated whereby theproduct line shear valve 116 closes in response to the service switch248 being set to a “SERVICE” setting so that the internal fuel dispenserpiping 124 carrying the fuel 80 to the fuel filter 128 is depressurizedas previously discussed. The process starts the same as described inFIG. 8 between blocks 300-308. After step 308 is performed in FIG. 8,the process goes to block 330 in FIG. 9 where the service switch 248 isset to the “SERVICE” setting 258. Thereafter, the vent 252 is opened toallow air to come into the conduit 264 that causes a loss of vacuum inthe vacuum conduit 176 (block 332) and causes the vacuum actuator 186 toclose the product line shear valve 116 (block 334). Thereafter, theinternal fuel dispenser pipings 124 are depressurized due to the closingof the flow path in the product shear valve 116 (block 336). The serviceswitch 248 may also activate a signal to be sent over communication line249 coupled to the tank monitor 168 to alert the tank monitor 168 thatthe “SERVICE” setting 258 has been selected and that the product lineshear valve 116 has been closed as a result (block 338). Thereafter, thetank monitor 168 may shut down the STP 82 if so configured, so that themain fuel piping 106 on the inlet side of the product line shear valve116 is depressurized as well (block 340). The process returns to block302 in FIG. 8 whenever the service switch 248 is set back to the “RUN”setting 256 and a sufficient vacuum level is restored in the vacuumconduit 176.

Filter Interlock

Another aspect of the present invention takes advantage of thevacuum-actuated product line shear valve 116 to provide the automaticclosing of the product line shear valve 116 in response to servicing ofthe fuel filter 128 in the fuel dispenser 10. In this manner, servicepersonnel do not have to manually close the product line shear valves116 to depressurize the main fuel piping 106 when changing the fuelfilter 128 as a safety feature.

The fuel dispenser 10 typically contains a replaceable fuel filter 128inline to each internal fuel dispenser piping 124 to preventcontaminants from entering the fuel flow meter 56 and passing on to acustomer's vehicle, as is well known. Over time, service personnel mustremove and replace the fuel filter 128 with a new filter in order toprevent the fuel filter 128 from becoming clogged and blocking the flowof fuel 80 through the fuel dispenser 10. Because the fuel filter 124 iscoupled inline to the fuel delivery piping 124 of a fuel dispenser 10,the fuel 80 inside the fuel filter 128 and the piping 124 entering andleaving the filter is pressurized, thereby causing the potential of thefuel 80 to squirt out onto the service personnel when the fuel filter128 is removed. Therefore, since the present invention provides a methodand system of automatically closing the product line shear valve 116 inresponse to a vacuum loss, the present invention can also be designed tocause a vacuum loss in the vacuum conduit 176 and to the vacuum actuator186 to close the flow path of the product line shear valve 116 inresponse to the removal of a fuel filter 128 in the fuel dispenser 10.In this manner, the internal fuel dispenser piping 124 is depressurizedby closing off the STP 82 pump force from the fuel filter 128 by theclosing of the product line shear valve 116.

Turning again to FIG. 7, the conduit 264 is coupled to the vacuumconduit 176 and conduit 266 through use of a T-style fitting 260 andconnectors 246. Therefore, a loss in vacuum in conduit 266 will alsocause a loss in vacuum in the vacuum conduit 176, which will in turncause the vacuum actuator 186 to close the shear valve 116 as previouslydescribed. The conduit 266 is run outside of the fuel dispenser sump 24up into the fuel dispenser 10 and into an interlock valve 268 that iscoupled to fuel filter coupling 126 via fitting 272. A vent 270 iscoupled to the interlock valve 268. The interlock valve 268 can bemanually opened and closed, or can be designed so that in order forservice personnel to remove the fuel filter 128, the interlock valve 268must be opened. When the interlock valve 268 is opened (or closeddepending on the design), a vent 270 is opened, thereby allowing air toenter inside the conduit 266. This in turn causes a loss of vacuum inconduit 264, which also causes a loss of vacuum in the vacuum conduit176. The vacuum actuator 186 closes the product line shear valve 116 inresponse. Therefore, when the fuel filter 128 is to be changed, theautomatic closing of the product line shear valve 116 automaticallydepressurizes the internal fuel dispenser piping 124 coupled to the fuelfilter 128 as well as the fuel 80 trapped inside the internal fuelpiping 124, before it can be removed, thereby preventing the fuel fromsquirting onto service personnel due to the pressure build-up.

In the flowchart of FIG. 10, the process is illustrated whereby theproduct line shear valve 116 closes in response to the interlock valve268 being closed or opened. When the vent 270 is opened, a loss ofvacuum occurs in the vacuum conduit 176, thereby causing the vacuumactuator 186 to automatically close the product line shear valve 116 inresponse as a safety measure. The process is the same as described inFIG. 8 between blocks 300-308. After step 308 is performed in FIG. 8,the process goes to block 350 in FIG. 10, where the vent 270 is openedin response to an activation of the interlock valve 268 either manuallyor by a service personnel attempting to remove a fuel filter 128 insidethe fuel dispenser 10. The opening of vent 270 allows air to come intothe conduit 246 causing a loss of vacuum in the vacuum conduit 176, thuscausing the vacuum actuator 186 to close the product shear valve 116(block 352). Thereafter, the internal fuel dispenser piping 124 isdepressurized due to the closing of the product line shear valve 116(block 354). Service personnel can then replace the fuel filter 128 witha new filter without fear of pressurized fuel being present in theinternal fuel dispenser piping 124. After the fuel filter 128 isreplaced, the interlock valve 268 is reset to close vent 270 (block356). This allows a vacuum level to be regenerated in the vacuum conduit176 in order to cause the vacuum actuator 186 to eventually open theproduct line shear valve 116. The process returns to block 302 in FIG. 8whenever the service switch 248 is set to the “RUN” setting 256 fornormal operation.

Dispenser Sumps

The present invention also involves the use of an in-dispenser sump orcontainment pan 360 as an alternative or supplement to the below groundfuel dispenser sump 24, as illustrated in FIGS. 3 and 11. In thismanner, any leaks that occur in fuel-handling components located abovethe in-dispenser sump 360 are captured. The in-dispenser sump 360 may beused to effectively provide secondary containment for capturing leaksfor fuel-handling components internal to the fuel dispenser 10 whereproviding of secondary containment in other methods is not possible orimpracticable for space and/or cost reasons. In the illustratedembodiment, the in-dispenser sump 360 is comprised of a main plate 362that runs across the width of the fuel dispenser 10. The main plate 362contains protruding edges that tilt upward on the far ends of the mainplate 362 to capture leaks that occur above the main plate 362. The mainplate 362 is slanted upward on both sides of its center so that when aleak is captured by the main plate 362, gravity will pull and collectthe leak in the center of the main plate 362.

The main plate 362 contains orifices 373 for the internal fuel dispenserpiping 118, 134 to run through the main plate 362 to other components ofthe fuel dispenser 10 above the plate 362. The piping 118, 134 aresealed around the orifice 373 with a potting or epoxy compoundtypically. In this manner, any leaked fuel captured by the main plate362 will gravitate and pool up in the center of the main plate 362without leaking through the orifice 373. A low level liquid sensor 366is placed proximate to the center of the main plate 362, and preferablyin a trough or catchment container 374 either coupled to the main plate362 or integrally formed into the main plate 362, at the lowest level todetect any presence of leaked fuel 80. A high level liquid sensor 367 isplaced similarly, but at a designated liquid level to only detect whenleaks accumulate to a certain defined liquid level in the in-dispensersump 360 as a redundancy sensor in case the low level liquid sensor 366fails. Both the low level liquid sensor 366 and the high liquid levelsensor 367 are communicatively coupled to the DSM 170 via communicationlines 369 so that such leaks are detected and communicated to the DSM170. The DSM 170 provides for controlling the secondary containment ofthe fuel dispenser 10 in the service station as will be described belowin this application.

Because the main plate 362 acts to capture leaks, the main plate 362 mayalso be secondarily contained in case the main plate 362 is breached orcontains a leak to prevent the captured fuel 80 from leaking to theenvironment. Thus, the in-dispenser sump 360 is comprised of adouble-walled plate structure. The main plate 362 is supported by anouter, secondary plate 364. An interstitial space 365 is formed by thespace between the main plate 362 and the secondary plate 364. In thismanner, the interstitial space 365 will hold any leaks that occur as aresult of a breach or leak in the main plate 362 when a leak hasoccurred in a fuel-handling component located above the main plate 362.Because of the interstitial space 365 provided, this interstitial space365 can be monitored for leaks or breaches using a vacuum-generatingsource, just as previously described above for the below ground fueldispenser sump 24 and other fuel-handling components. Further, if theinterstitial space 365 of the in-dispenser sump 360 is fluidly coupledto the vacuum conduit 176 that is connected to the vacuum actuator 186of the product line shear valve 116 as illustrated in FIG. 7, a leak inthe in-dispenser sump 360 will cause a loss of vacuum that will causethe product line shear valve 116 to automatically close, therebypreventing more fuel 80 from reaching the leaky fuel-handling componentthat is causing the leak captured by the main plate 362.

An interstitial liquid sensor 368 may also be fluidly coupled to thedispenser sump interstitial space 365 to detect leaks in theinterstitial space 365. If a leak is detected, a signal will becommunicated to the DSM 170. The DSM 170 can in turn control devicesthat are designed to cause a loss of vacuum at the vacuum actuator 186to cause the product line shear valve 116 to close automatically.

If a below ground fuel dispenser sump 24 is provided as an alternativeto the in-dispenser sump 360, the below ground fuel dispenser sump 24may also be fitted with the interstitial liquid sensor 368 that isfluidly coupled to its interstitial space 27 so that a breach of theinner container 26 of the below ground fuel dispenser sump 24 will alsocause a signal to be generated to the DSM 170. Again, the DSM 170 cancause a loss of vacuum at the vacuum actuator 186 to automatically closethe product line shear valve 116. As an alternative, a brine solutionmay be used to fill the interstitial space 27 using a brine sensor (notshown) to detect a leak in the below ground fuel dispenser sump 24.Further, this embodiment may be used for customers that do not employfuel dispensers 10 containing an in-dispenser sump 360, but rather abelow ground fuel dispenser sump 24.

Dispenser Sensor Module (DSM)

FIG. 12 illustrates more detail of the secondary containment monitoringand control system for the in-dispenser sump interstitial space 365 andinternal fuel dispenser piping interstitial spaces 123, 139 to detectleaks, as described above. As illustrated, the DSM 170 provides variousinterfaces to components used to monitor and detect leaks as will bedescribed in more detail throughout the remainder of this application.Some of these features are described generally below with respect toFIG. 12. The remaining figures and descriptions that follow describethese features and functions in more detail.

Leak Sensors

As illustrated in FIG. 12, the DSM 170 contains a pressure transducer386 that is fluidly coupled to the interstitial liquid sensor 368 andthe in-dispenser sump interstitial space 365. Thus, when a leaks occursin the in-dispenser sump interstitial space 365, either a liquid leak isdetected by the interstitial liquid sensor 368, or pressure variationsdue to loss of vacuum are detected by the pressure transducer 386. Ineither case, this condition is communicated to DSM 170 for processingand providing control, including causing the vacuum actuator 186 to losevacuum and close the product line shear valve 116 as a result, whichwill be described below.

End-of-Zone Sensors

End-of-zone or end-of-line sensors (VSI) 376, 381 that are fluidlycoupled to ends of the interstitial spaces or lines of the internal fueldispenser and vapor piping interstitial spaces 123, 139 may also beprovided via ports 379, 383. If the end-of-zone sensors 376, 381 do notdetect a sufficient vacuum level present in these interstitial spaces123, 139 when a vacuum-generating source is applied, this is anindication of either a leak or blockage in the interstitial spaces 123,139. If a blockage exists in the interstitial space 123, 139, pressurevariations may not be detectable by the end-of-zone sensors 376, 381since the sensors 376, 381 are closed off from vacuum generated in theinterstitial spaces 123, 139. The end-of-zone sensors 376, 381 providesignals to the DSM 170 to allow this condition to be detected for properoperation of the system.

Redundant Vacuum Sources

Because a vacuum-generating source applies a vacuum to the internal fueldispenser piping interstitial spaces 123, 139, this samevacuum-generating source can also be used to apply a vacuum to thein-dispenser sump interstitial space 365 or below ground fuel dispensersump interstitial space 27 for monitoring of leaks as well as aconvenience. In this manner, a separate vacuum-generating source is notrequired to draw a vacuum level in the fuel dispenser sump interstitialspaces 27, 365 for monitoring of leaks. This is particularly beneficialif an in-dispenser sump 360 is used in the dispenser 10, as illustratedin FIG. 12, is because the in-dispenser sump 360 is located inrelatively close proximity to the internal fuel dispenser piping 118.

Two of the end-of-zone sensors 376 for the product piping interstitialspaces 123 are fluidly coupled to latching valves 380A, 380B (CV-1A,CV-1B), which are both fluidly coupled to the pressure transducer 386,the interstitial liquid sensor 368 and the in-dispenser sumpinterstitial space 365. Note that both Product A and Product B'sinterstitial space 123 is fluidly coupled to the in-dispenser sumpinterstitial space 365 via the latching valves 380A, 380B. In thismanner, a vacuum-generating source applying a vacuum to either Product Aor Product B's interstitial space 123 can be used to also generate avacuum level in the in-dispenser sump interstitial space 365. Thein-dispenser sump interstitial space 365 is only fluidly coupled to oneof the product's interstitial spaces 123 at a time since the latchingvalves 380A, 380B are controlled for only one to open at a time. In thismanner, if the vacuum-generating source cannot maintain a vacuum levelin a particular product piping's interstitial space 123 due to a leak inthat product's internal fuel dispenser piping 118, the latching valve380A, 380B opening can be switched so that the in-dispenser sumpinterstitial space 365 can be drawn under a vacuum from anotherproduct's interstitial space 123. This system provides a redundancy forthe vacuum source to the in-dispenser sump interstitial space 365 sothat it can be continued to be monitored for leaks, even if one of theinternal fuel dispenser product lines 118 contains a leak sufficient fora loss of vacuum to occur to prevent its vacuum level from being able toproperly generate a vacuum level in the in-dispenser interstitial space365.

Note that a redundant system is not required for the present invention.Only one product line's interstitial space 123 may be coupled to thein-dispenser sump interstitial space 365. Further, more than two productlines' interstitial spaces 123 may be coupled to the in-dispenser sumpinterstitial space 365 if triple or greater redundancy is desired. Inthis case, another latching valve 388 would be provided for the extrainterstitial space 123 sources so that only one is coupled to thein-dispenser sump interstitial space 365 to generate a vacuum level forleak monitoring at one time.

Also, note that the product line interstitial space 123 may be fluidlycoupled to the below ground fuel dispenser sump 24, and in particularlyits interstitial space 27 (as illustrated in FIG. 1) in a similar mannerto use the same vacuum-generating source to draw a vacuum in the fueldispenser product lines 118 and the below ground fuel dispenser sumpinterstitial space 27 as well.

Vacuum Actuator Shear Valve Control

The DSM 170 controls a pilot control valve (CV-3) 390 in order topneumatically control the opening and closing of the product line shearvalves 116 via control of the vacuum actuators 186. The pilot controlvalve 390 is activated to couple a vacuum from the dispenser productlevel 118 that is also coupled to the fuel dispenser sump 24, 360 togenerate a vacuum level in the dispenser sump interstitial spaces 37,356. Thus, if the pilot control valve 390 couples the vacuum level tothe vacuum actuator 186, the product line shear valves 116 will be open.The vacuum actuators 186 and their control of the product line shearvalves 116 was previously described in detail with regard to FIGS. 4-6.If the DSM 170, through its components, detects a leak or breach in thesecondary containment systems, including the internal fuel dispenserpiping 118, 134, or the in-dispenser sump 360 or below ground fueldispenser sump 24, the DSM 170 causes the pilot valve 390 topneumatically cause a loss of vacuum to be applied to the vacuumactuators 186 on the product line shear valves 116 to close the shearvalves 116 as well be described in more detail below and illustrated inFIG. 13.

Exemplary Secondary Containment Monitoring and Control SystemArchitecture and Operation

Now that monitoring and control components of the secondary monitoringand control system have been described in general, the application nowdescribes the operation of the system in more detail with respect to apreferred embodiment. FIGS. 13-19 describes this embodiment of anoverall secondary containment and monitoring system according to thepreferred embodiment present invention.

DSM Package

As an introduction to the control module for the secondary containmentand monitoring system according to one embodiment, FIG. 13 illustratesthe DSM 170 package and its various ports and interfaces to provide thesecondary containment monitoring and control system in accordance withone embodiment of the present invention. These interfaces and functionswill be described in more detail below. However, these elements arebriefly introduced herein with respect to FIG. 12.

The DSM 170 contains the necessary hardware and electronics related tothe secondary containment and monitoring system for individual fueldispensers 10 in the system. A DSM 170 is provided for each fueldispenser 10. The DSM 170 is provided in an enclosure that resides inthe hydraulics cabinet of the fuel dispenser 10 or underneath the belowground fuel dispenser sump 24. These areas are Class 1, Division 1 areasrequiring intrinsically safe connections. The enclosure is sealed fromenvironmental conditions, such as water, fuel, oil, and vapors. Theenclosure provides connections for the electrical and pneumaticcomponents and accessories to provide the secondary containmentmonitoring and control system as described herein.

As illustrated in FIGS. 12 and 13, the DSM 170 contains ports 379, 383to couple to the internal fuel dispenser piping interstitial spaces 123,139, or more generally the fuel dispenser piping 118 and the vaporreturn piping 134. The ports 379, 383 may be designed to connect to ¼inch vacuum tube with a 7/16″-20 SAE threaded fitting to connect theports 379, 383 to couple the interstitial spaces of the product lines123 and the vapor line 139 for example. The ports 379, 383 can either bemolded, machined, bonded, or ultrasonically welded to the DSM 170

As previously described above, the DSM 170 coupling to the interstitialspaces of the product lines 123 and vapor line 139 allows the DSM 170 tocouple the pressure transducer 368 to these spaces for detection of aleak via pressure variation monitoring as previously described andillustrated in FIG. 12. A similar port 400 is provided to the couple thepressure transducer 368 to the dispenser sump interstitial space 365 formonitoring the in-dispenser sump 360 for leaks as well, as previouslydescribed and illustrated in FIG. 12.

Ports 394, 396, 398 are provided for the DSM 170 to interface to theinterstitial liquid sensor 368 and the in-dispenser sump low levelliquid sensor 366 and below ground fuel dispenser liquid sensor 234 (thefloat) to detect liquid leaks in the fuel-handling components aspreviously discussed and illustrated in FIG. 11. These ports allow theDSM 170 to detect a liquid leak in either the interstitial space 365, 27of the dispenser sumps, or their inner containers 362, 26 as part of thecontrol system 46.

The DSM 170 contains an interface to the tank monitor 168. Some of thedecision making and logic of the control system may reside in the tankmonitor 168 as opposed to the DSM 170, as well be discussed below. Forconnections between the DSM 170 and components in the fuel dispenser 10,including power and status, an IS barrier connection 406 is provided onthe DSM 170. Since the DSM 170 is obtaining power from the fueldispenser 10 for some of its components, the DSM 170 must interfacethrough an IS barrier of the fuel dispenser 10 into a protected Class 1,Division 1 area. The DSM 170 also contains a port 402 for otherconnections to door switches and the in-dispenser sump low level liquidsensor 366, which are used by the DSM 170 to actuate the product lineshear valves 116 to close among other conditions when activated.

A reset button 408 is provided to reset the electronic controllers (e.g.microcontrollers) inside the DSM 170 in case of a hardware hang-up. Thereset button 408 may be a SPST momentary “on” type switch, such that theamount of time the switch is depressed will not effect operations orcontrol by the DSM 170.

Circuit Diagram

FIG. 14 contains an overall view and illustration of the circuit diagramof the secondary containment monitoring and control system according tothe preferred embodiment present invention. Several of the control andmonitoring components are disclosed which provide electronic control ofcertain features and functions described below. In this embodiment, theDSM 170 consists of two distinctly powered portions indicated as the“Dispenser-Powered Portion” 410 and the “TLS Powered Portion” 411. The“TLS” is the tank monitor 168. The “Dispenser-Powered Portion” 410contains a dispenser-powered microcontroller 412 on a printed circuitboard (PCB) to provide a means to accept power from a source other thanthe tank monitor 168. The first microcontroller 412 receives power fromthe fuel dispenser 10 through an intrinsically safe connection(illustrated in FIG. 16).

One function of the dispenser-powered microcontroller 412 is tointerface with the 3-way solenoid pilot control valve (CV-3) 390(previously illustrated and discussed in FIG. 12) to communicate withand control the vacuum actuators 186 to close the product line shearvalves 116 according to designed logic conditions being present. Moredetails on the pneumatic operation of the pilot control valve 390 andits communication to the vacuum actuators 178 is described later belowand illustrated in FIG. 15. Control of the pilot control valve 390 isone of the more critical functions since this valve controls the vacuumactuators 178 that control the closing of the product line shear valves116 in response to a leak or other condition where closing the productline shear valves 116 is desired. These conditions are described in moredetail below.

The dispenser-powered microcontroller 412 accepts as inputs, dispenserdoor switches 422, 424, the reset switch 408, and the in-dispenser sumplow liquid level sensor 366, as illustrated in FIG. 14. If thedispenser-powered microcontroller 412 receives a signal from one of thedispenser door switches 422, 424, which indicates that a fuel dispenser10 cabinet door 23 (illustrated in FIGS. 1 and 3) has been opened, themicrocontroller 412 instructs the pilot control valve 390 to communicatewith the vacuum actuators 186 to close the product line shear valves 116as a safety precaution. There is typically one door switch 422, 424 perfuel dispenser door. There are typically two doors 23 per fuel dispenser10; one on each side of the fuel dispenser 10. The door switches 422,424 are coupled to the dispenser-powered microcontroller 412 as opposedto a tank monitor-powered microcontroller 413 so that the pilot controlvalve 390 can continue to be controlled by the dispenser-poweredmicrocontroller 412 if the tank monitor 168 loses power or otherwisemalfunctions. The status of the door switches 422, 424 will also becommunicated from the dispenser-powered microcontroller 412 to the tankmonitor 168. This provides a status to the tank monitor 168 to indicatethat the product line shear valves 116 have been closed due to thecabinet door 23 opening.

If the dispenser-powered microcontroller 412 receives a signal from thein-dispenser sump low level liquid switch 366 indicating that a leak ispresent above the main leak plate 362, the microcontroller 412 instructsthe pilot control valve 390 to communicate with the vacuum actuators 186pneumatically to cause a loss of vacuum applied to the vacuum actuators178 to in turn close the product line shear valves 116 to prevent fuel80 from being further supplied to the source of the leak. Thein-dispenser low liquid level sensor 366 is coupled to thedispenser-powered microcontroller 412 so that the in-dispenser sump 360is continuously monitored regardless of the status of the tank monitor168. In this manner, if the tank monitor 168 loses power or malfunctionsin any other capacity, the in-dispenser sump 360 continues to bemonitored for leaks since it is powered by the dispenser-poweredmicrocontroller 412 rather than the-tank-monitor powered microcontroller413. The “Dispenser-Powered Portion” 410 of the DSM 170, and inparticular the dispenser-powered microcontroller 412, communicatesinformation to the fuel dispenser 10 via interface electronics 420coupled to optic-couplers 464 to a dispenser IS barrier 466. Asdiscussed in FIG. 16 below, status information may be communicated fromthe dispenser-powered microcontroller 412 to the fuel dispenser 10regarding the secondary containment monitoring and control systemthrough the dispenser IS barrier 466.

The dispenser-powered microcontroller 412 also communicates and receivesinformation to a second portion of the DSM 170 labeled the “TLS PoweredPortion” 411 through optic-couplers 414, 416 to a second, tankmonitor-powered microcontroller 413. The tank monitor-poweredmicrocontroller 413 is provided as part of a second PCB in the DSM 170that receives inputs from the below ground dispenser sump low levelliquid switch 234, the in-dispenser sump high level liquid sensor 367,and the interstitial liquid level switch 368. The tank-monitor poweredmicrocontroller 413 communicates with the tank monitor 168 via interfaceelectronics 418 using a protocol, such as the Veeder-Root Smart Sensorprotocol for example. If any of these switches or sensors indicates aleak in any monitored interstitial space of a fuel-handling component orliquid in the fuel dispenser sump 24, 360, the status is communicated tothe tank monitor 168. The logic of the tank monitor 168 can direct thedispenser-powered microcontroller 412 to close the pilot control valve390, which in turn causes a loss of vacuum that will cause vacuumactuators 186 to close the product line shear valves 116 if any of theseswitches indicates a leak.

The tank monitor 168 continuously updates a pilot control valve 390 opensignal and sends this signal to the dispenser-powered microcontroller412 via the tank monitor-powered microcontroller 413. The tank monitor168 must continue to update the pilot control 390 valve open signal inorder for the dispenser-powered microcontroller 412 to keep the pilotcontrol valve 390 opened to in turn keep the product line shear valves116 opened. The dispenser-powered microcontroller 412 contains a timeoutcircuit to ensure that the pilot control valve 390 status signal isreceived by the tank monitor 168 with a specified period. If either thebelow ground dispenser sump low level liquid switch 234, thein-dispenser sump high level liquid switch 367, or the interstitialliquid level sensor 368 indicate a leak, the tank monitor 168 will notsend an updated pilot control valve 390 open signal. This will cause thedispenser-powered microcontroller 412 to timeout waiting for-thepilot-control valve 390 open signal and in response close the pilotcontrol valve 390 thereby causing a loss of vacuum at the vacuumactuators 178. This will in turn cause the product line shear valves 116to close. Further, because of this timeout design, any loss of power ormalfunction in the tank monitor 168 that prevents the tank monitor 168from sending out an updated pilot control valve 390 open signal whichwill cause the dispenser-powered microcontroller 412 to close the pilotcontrol valve 390 to cause the loss of vacuum to in turn close theproduct line shear valves 116 as a safety precaution.

Because control of the pilot control valve 390 is critical in thesecondary containment and monitoring system, it was designed for thedispenser-powered microcontroller 412 rather than the tankmonitor-powered microcontroller 413 to control the pilot control valve390. In this manner, if the tank monitor 168 loses power or otherwisemalfunctions, the dispenser-powered microcontroller 412, by beingindependently powered, can close the pilot control valve 390 to in turnclose the product line shear valves 116 even if the tank monitor 168malfunctions.

The below ground dispenser sump low level liquid sensor 234 is coupledto the tank-monitor powered microcontroller 413. The sensor 234communicates whether leaked fuel has been collected in the below grounddispenser containment sump 24. This sensor 234 is coupled to the tankmonitor-powered microcontroller 413 so that the tank monitor 168 canmonitor the leak status during its normal polling process. If the tankmonitor 168 determines that a leak is contained in the below grounddispenser sump 24, the tank monitor 168 will not update the pilotcontrol valve 390 open signal, which will in turn cause the pilotcontrol valve 390 to be closed by the dispenser-powered microcontroller412, causing a loss of vacuum at the vacuum actuators 178. This willclose the product line shear valves 116 for the fuel dispenser 10 whosebelow ground dispenser sump 24 captured a leak.

The in-dispenser sump high liquid level sensor 367 is also coupled tothe tank monitor-powered microcontroller 413. The sensor 367communicates the status of the in-dispenser sump 360 and whether it hascaptured a leak at the prescribed level detected by the sensor 367, tothe tank monitor-powered microcontroller 413. The in-dispenser sump highliquid level sensor 367 is coupled to the tank monitor-poweredmicrocontroller 413 since the sensor 367 is not provided as part of theDSM 170. The fuel dispenser 10 manufacturer decides if the sensor 367will be provided as part of their fuel dispenser 10. If the tank monitor168 detects a leak via a status of the in-dispenser sump high liquidlevel sensor 367, the tank monitor 168 may direct the dispenser-poweredmicrocontroller 412 to close the pilot control valve 390 to in turnclose the product line shear valves 116 for the fuel dispenser 10containing the leak to cut off the source of fuel 80 provided to theleak.

The interstitial liquid level sensor 368 is also coupled to the tankmonitored-powered microcontroller 413. This sensor 368 communicates thestatus of the interstitial liquid level of the interstitial space 365 ofthe in-dispenser sump 360. The sensor 368 status is checked by the tankmonitor 168 polling process. If the tank monitor 168 detects a leak viastatus of the interstitial liquid level sensor 367, the tank monitor 168may direct the dispenser-powered microcontroller 412 to close the pilotcontrol valve 390 to in turn close the product line shear valves 116 forthe fuel dispenser 10 containing the leak to cut off the source of fuel80 provided to the leak.

The pressure transducer 386, the latching valves 380A, 380B(CV-1A;CV-1B) and the end-of-zone vacuum switches 376, 381 are also allcoupled to the tank monitor-powered microcontroller 413. Thesecomponents were previously described above with respect to FIG. 12.

The pressure transducer 386 is coupled to both the interstitial space ofboth the product lines 118 and one or both of the dispenser sumps 360,24 as previously described in FIG. 12. If a leak occurs in theseinterstitial spaces 123, 365, 27, the pressure transducer's 386 measuredpressure variation will be sensed by the tank monitor-poweredmicrocontroller 413, which will in turn be communicated to the tankmonitor 168 as part of its polling process. The tank monitor 168 will inturn direct the dispenser-powered microcontroller 412 to close the pilotcontrol valve 390, which will in turn cause the product line shearvalves 116 to be closed as a result of the leak.

The latching valves 380A, 380B are controlled by the tankmonitor-powered microcontroller 413 to provide the redundant vacuumsource generation for one or both of the dispenser sumps 360, 24. Avacuum level generated by a vacuum-generating source in the internalfuel dispenser piping interstitial space 123 is tapped off of to alsodraw a vacuum level in the dispenser sump interstitial space 365, 27, aspreviously described and illustrated in FIG. 12, for monitoring ofleaks. The tank monitor 168 only opens one of the latching valves 380A,380B at a time, so that the vacuum generated in the dispenser sumpinterstitial space 365, 27 is only generated from the vacuum levelgenerated in one product line's interstitial space 123. If a leak occursin that product line's interstitial space 123 such that the a vacuumlevel cannot be maintained in the dispenser sump interstitial space 365,27, the tank monitor 168 can open the other latching valve 380A, 380B toswitch the source of vacuum generation to the dispenser sumpinterstitial space 365, 27 to another product line interstitial space123. In this manner, the dispenser sump 360, 24 can continue to bemonitored for leaks even if a particular product line cannot maintain asufficient vacuum level due to a leak.

The end-of-zone switches 376, 381 are provided for each of the productlines 118 and the vapor return line piping 140 to detect if a vacuum isbeing properly generated to the end of each line, as previouslydiscussed. The end-of-zone switches 376, 381 are placed at the end ofeach interstitial spaces 123, 139 of the product lines 118 and the vaporreturn line 140. In this manner, when a vacuum is generated in theproduct piping or vapor return line piping 118, 140, the tankmonitor-powered microcontroller 413 can communicate the status of theend-of-zone switches 376, 381 to the tank monitor 168. The tank monitor168 can in turn detect if a vacuum is being properly generated all theway to the end of the interstitial spaces 123, 139. If a vacuum level isbeing generated, but an end-of-zone switch 376, 381 is not properlyswitching due to a vacuum level being present at the end of aninterstitial space line 123, 139, this is an indication of that blockageexists in the interstitial space 123, 139 since the vacuum level is notreaching the end of the interstitial space line 123, 139. Thus, withoutthe end-of-zone switches 376, 381, the system could not distinguish ablocked line from an un-blocked line.

Pneumatic System Diagram

Now that the electrical elements of the secondary containment monitoringand control system of the preferred embodiment have been described, thepneumatic components and control functionality of the system will now bedescribed with respect to FIG. 15.

FIG. 15 illustrates a pneumatic diagram of the secondary containmentmonitoring and control system according to the preferred embodiment.There are three product lines shown labeled “Product Line #1,” “ProductLine #2,” and “Product Line #3.” These lines are the product lines 118for each fuel grades provided to the fuel dispenser 10. If the fueldispenser 10 was a blending fuel dispenser, only two gasoline productlines would be provided as disclosed in FIG. 3; one fuel piping line 118for the low grade of gasoline, and one fuel piping line 118 for the highgrade of gasoline. The vacuum-generating source is fluidly coupled tothe main fuel piping interstitial space 111, which extends through theinterstitial space of double-walled shear valve 116, and into theinterstitial space of the internal fuel dispenser piping 123. In a likemanner, the vacuum-generating source is also fluidly coupled to thevapor line piping interstitial space 145, which extends through theinterstitial space of the double-walled vapor line shear valve 117 andinto the internal vapor line piping interstitial space 139. The systemobtains its vacuum from the vacuum-generating source applying a vacuumto the main fuel piping interstitial space 111 and the vapor returnpiping interstitial space 145 in this embodiment.

The product line shear valves 116 are coupled to vacuum actuators 186 aspreviously described and as illustrated in FIG. 15. Since there arethree fuel dispenser piping lines 118, there are three vacuum actuator186 and product line shear valve 116 combinations for each of the lines118. FIG. 15 only illustrates the product line interstitial spaces 111,123 on the inlet and outlet side of the product line shear valve 116,since the vacuum level is generated in the product line interstitialspaces 111, 123. The product line shear valves 116 are double-walledshear valves so that product line interstitial space 111 is coupled toproduct line interstitial space 123, like illustrated in FIGS. 4-6. Whenno vacuum is present in the system initially, the product line shearvalve 116 is closed since no vacuum is being applied to the vacuumactuator 186 to keep the product line shear valve 116 flow path open.

Before discussing the pneumatic components in FIG. 15, the vacuum flowpath opening the system is discussed. The vacuum is originallyestablished by the vacuum-generating source in the product lineinterstitial space 123. From there, the vacuum is coupled to anoperability valve 430, which is coupled to the product line interstitialspace 123. The vacuum extends to a vacuum conduit 431 coupled to theoutput of the operability valve 430 and extends through a filter 438into a second vacuum conduit 442. The filter 438 keeps debris fromflowing back to the shear valve 116 interstitial space.

The second vacuum conduit 442 is coupled to the end-of-zone switch 376and passes to the latching valves 380A, 380B, which control whether thevacuum is applied to the vacuum conduit 450 coupled to the dispensersump interstitial space 365, 27. The end-of-zone switch 376 willactivate if a sufficient vacuum level is present thereby indicating thatthe vacuum level was able to reach the end of the product lineinterstitial space 123 and thus no blockage exists, as previouslydiscussed. Only one of the latching valves 380A, 380B is open at onetime. This provides a redundant vacuum source to generate a vacuum inthe dispenser sump interstitial space 365, 27, as previously discussed.

The vacuum is then passed from the output of the latching valves 380A,380B to the pilot control valve 390 via a vacuum conduit 452. The pilotcontrol valve 390 controls whether the vacuum level is communicated viaa pilot valve vacuum conduit 456 to dedicated pilot control valves 458(CV-2) that control whether the vacuum will be communicated to thevacuum actuator 186. The pilot control valves 458 control whether thevacuum actuator 186 keeps the product line shear valves 116 opened,since the vacuum from the pilot control valves 458 is coupled to thevacuum actuator 186 via a shear tube or conduit 176. If the pilotcontrol valve 390 is opened to all on the vacuum level to becommunicated to the dedicated pilot valves 458, the vacuum level willrejoin its origination at the output of the operability valve 430 via avacuum conduit 461.

Thus, in summary the pneumatic system of FIG. 15 directs a vacuum levelgenerated by a vacuum-generating source in the product line interstitialspace 111, 123 to (1) components that determine if a blockage exists inthe interstitial space 365 (end-of-zone switch 376), (2) redundantlycontrolled latching valves 380A, 380B to generate a vacuum in thedispenser sump interstitial space 365, 232: and (3) to a pilot controlvalve 390 that directs and controls the vacuum level in order to actuateand open the product line shear valves 116. In this manner, a sufficientvacuum will have to be established first in the product lineinterstitial space 111, 123 and the dispenser sump interstitial spaces365, 27 before a sufficient vacuum level is applied to the vacuumactuators 178. The product line shear valves 116 are purposefullydesigned to open last as part of the pneumatic design so that fuel 80 isnot supplied until the integrity of the entire system (via monitoringfor leaks in the interstitial spaces) is performed and established. Aspreviously discussed, there are other electrical sensors and events thatcan also cause the pilot control valve 390 to cause the product lineshear valves 116 to close for other reasons as well.

Now that the vacuum path for the system has been discussed forestablishing a vacuum level to monitor for leaks of the fuel-handlingcomponents, a detailed discussion of the pneumatic components and theiroperation and control of the vacuum is now discussed.

As illustrated in FIG. 15, the product line operability valve 430 iscoupled inline in the internal fuel dispenser piping 123 on the outletof the product line shear valve 116. The product line operability valve430 is a manually-controlled valve used to control and allow vacuumgenerated in the product line interstitial space 123 to be used tosupply vacuum to the fuel dispenser 10, and in more particular thedispenser sumps 24, 360, and the vacuum actuator 186 to open the productline shear valves 116 when no leak exists. When the product lineoperability valve 430 is not actuated, it is open (N.O. path). In thismanner, the vacuum level generated in the product line interstitialspace 123 is coupled to the vacuum conduit 431, through the filter 438and to the vacuum conduit 442. The product line operability valve 430 isopen unless manually actuated and closed (N.C. path).

The product line operability valve 430 is closed when an operabilitytest is desired to be performed by service personnel. The operabilitytest allows verification of the operation of the end-of-zone switches376 as well as the vacuum actuated product line shear valves 116. Whenclosed, the vacuum level from the product line interstitial space 123 isisolated from the dispenser sumps 24, 360 and the vacuum actuator 186 ofthe product line shear valves 116. The vacuum present in the vacuumconduit 431 is vented to atmosphere via an operability vent 432. Thisloss of vacuum causes a loss of vacuum in the vacuum flow path of thevacuum conduit 442, which will be detected by the end-of-zone switch 376and communicated to the tank monitor 168. Further, the loss of vacuumcauses a leak to be detected by the pressure transducer 386. The tankmonitor 168 can then ensure the end-of-zone vacuum switches 376 areworking properly. Further, the tank monitor 168 will cause the pilotcontrol valve 390 to pneumatically cause a loss of vacuum to becommunicated to the dedicated pilot valves 458 to close the product lineshear valves 116 as will be discussed in more detail below. Thus,service personnel can verify the correct operation of the end-of-zoneswitches 376 and closing of the product line shear valves 116 when theoperability valve 430 is actuated.

A vapor line operability valve 434 is also provided for the vapor linemonitored interstitial space 145, 139 just like the operability valve430 for the product lines 111, 123. The actuation of vapor lineoperability valve 434 is just like that of the product line operabilityvalve 430.

Because the operability valves 430, 434 are mapped on a one-to-onerelationship with the end-of-zone vacuum switches 376, 381, theoperability valves 430, 434 provide a convenient method to assistinstallation personnel in correctly mapping the tank monitor 168 to thecorrect end-of-zone vacuum switches 376, 381. It is important for thetank monitor 168 to correctly associate the end-of-zone switches 376,381 so that a blockage can be detected and identified in the correctproduct and vapor line interstitial space 123, 139.

The product line operability valve 430 can also be used to manually shutoff the product line shear valves 116 for any other purpose desired byservice personnel. When service personnel desire to put the system backinto operation, service personnel need only release the operabilityvalve 430 actuation. Thereafter, the vacuum-generating source willeventually generate a sufficient vacuum, if no leaks are present, toautomatically open the product line shear valves 116 via the vacuumactuator 186 previously described. This is an improvement over priorshear valve systems where a linkage on the shear valve had to bemanually reset to open the flow path inside the shear valve, thusproviding for a greater possibility of damaging the shear valve.

As the vacuum level increases in the vacuum conduits 442, 446, theend-of-zone switches 376, 381 will be actuated at a designed vacuumlevel. The end-of-zone switches 376, 381 are vacuum switches thatmonitor vacuum pressure. The switches 376, 381 have a fixed vacuum levelset point and will actuate from a normally open position (N.O.) to anormally closed (N.C.) position upon the vacuum level reaching the setpoint. The set point may be set to actuate at −3.5 psi with a ± 5% forexample.

The end-of-zone switches 376, 381 will actuate from the N.C. to the N.O.position when the vacuum levels decrease slightly from the set point ofthe switches 376, 381. The tank monitor 168 will poll the end-of-zoneswitches 376, 381, via the tank monitor-powered microcontroller 413, toknow that a sufficient vacuum level has been established to the vacuumpaths of the system.

After the tank monitor 168 ensures that a sufficient vacuum is drawn byuse of the end-of-zone switches 376, 381, the tank monitor 168 willcontrol the correct latching valve 380A, 380B to open the vacuum flowpath to be coupled to vacuum conduit 448 so that the vacuum-generatingsource can begin to draw a vacuum in vacuum conduit 450 coupled to thedispenser sump interstitial spaces 365, 27. The tank monitor 168 employsan algorithm to determine which latching valve 380A, 380B is to beopened and which is to be closed. In one embodiment, the latching valves380A, 380B are solenoid valves that contain a shuttle mechanism thattoggles between an open and closed state and does not require constantpower to stay engaged in either position. The inductance of the solenoidcoil can be measured as part of the tank monitor 168 polling cycle todetermine if the latching valves 380A, 380B are opened or closed. Thetank monitor 168 can then actuate the latching valves 380A, 380B to anopen or closed position as desired. In this manner, the tank monitor 168is able to control the latching valves 380A, 380B to ensure that aredundant source of vacuum is available to generate a vacuum level inthe dispenser sump interstitial space 365, 27 and the rest of thesystem, even if one of the dispenser product lines 118 that is tappedoff of to provide the vacuum source contains a leak. Again, theend-of-zone switches 376 allow the tank monitor 168 to know if aparticular product line 118 can provide a sufficient vacuum to make thisdecision.

Note that “Product Line #3” (118) and “Vapor Line” (134) do notinterface to a latching valve 380. This is because these lines are notused as a vacuum source for the rest of the system. However, end-of-zoneswitches 376, 381 are still provided to ensure that a sufficient vacuumlevel is generated to the end of these product line and vapor lineinterstitial spaces 123, 139 as part of the leak monitoring system.These end-of-zone switches 379, 381 are also monitored by the tankmonitor 168. The tank monitor 168 will cause the pilot control valve 390to close thereby causing a loss of vacuum to the vacuum actuator 186 toclose product line shear valves 116 if a sufficient vacuum cannot beestablished to the end of the monitored interstitial space lines 123,139, either due to a leak or blockage.

Once the system has a sufficient vacuum level, the tank monitor 168 willopen one of the latching valves 380A, 380B to begin to generate a vacuumin the dispenser sump interstitial spaces 365, 27. The tank monitor 168monitors the pressure transducer 386 to monitor the vacuum level in thedispenser sump interstitial space 365, 27. The tank monitor 168determines if the vacuum level in the dispenser sump interstitial space365, 27 is at a sufficient vacuum level for monitoring of leaks. Whenthe vacuum level is sufficient, meaning that there is no leak in thefuel dispenser sump interstitial space 365, 27, the tank monitor 168instructs the latching valve 380A, 380B that was opened to provide thevacuum source to close, thereby isolating the dispenser sumpinterstitial space 365, 27 into a separate zone from the dispenserpiping interstitial space 123.

The tank monitor 168 continues to poll the pressure transducer 386 forloss of vacuum. If a vacuum loss occurs in the dispenser sumpinterstitial space 365, 27, the tank monitor 168 opens one of thelatching valves 380A, 380B to attempt to replenish the vacuum level inthe dispenser sump interstitial space 365, 27. If the vacuum level issufficient in the dispenser sump interstitial space 365, 27, this vacuumlevel is pneumatically communicated to the pilot control valve 390,which is dead-headed (i.e. not coupled to the pilot valve vacuum conduit456). The pilot control valve 390 is a solenoid valve in one embodimentthat is initially dead-headed in the system. The dispenser-controlledmicrocontroller 412 as part of the DSM 170, receives a periodic signalfrom the tank monitor 168 indicating the control status of the pilotcontrol valve 390. As previously discussed, the tank monitor 168 willonly indicate that the status of the pilot control valve 390 is to beopened if all other sensors and conditions do not indicate a leak, orother safety conditions previously described where it is desired toclose the product line shear valves 116 is not present. The controlstatus is stored by the dispenser-powered microcontroller 412 and isused to control the state of the pilot control valve 390. If there is noupdate, the dispenser-powered microcontroller 412 will energize thepilot control valve 390 to close or stay closed. If the tank monitor 168indicates that all vacuum levels and other sensors are in a normalstatus, the vacuum level is continued propagating through the systemtowards opening of the product line shear valves 116.

Once the pilot control valve 390 is energized, the vacuum source fromthe vacuum conduit 452 is coupled to the vacuum conduit 456 coupled tothe dedicated product line pilot valves 458. A diaphragm (not shown inFIG. 15) in the product line pilot valves 458 is opened by the vacuumpower, and the pilot valve 458 is switched from the normally open (N.O)to the normally closed (N.C.) position. At this point, the vacuum levelis coupled to the vacuum actuator 186 of the product line shear valves116 via the vacuum conduit, labeled “shear tube” 176. The vacuum levelwill cause the product line shear valves 116, to open since the vacuumlevel is properly established through the entire secondarily containedspace of the system. The present invention is designed to open theproduct line shear valves 116 last, since they control fuel 80 flow. Inthis manner, the integrity of the system is determined fully before fuel80 flow is allowed.

Further, by the pilot valve 458 moving to the N.C. position, the pilotvalve vacuum conduit 456 is also coupled to a vacuum conduit 461 at thevacuum level origination point to come around full circle. Thus, if thevacuum level in the product line interstitial spaces 123 drops below asufficient vacuum level possibly indicating a leak or blockage, theproduct line shear valves 116 are closed independently of the dispensersump interstitial space 365, 27 leak status and its operation.

If a leak or other condition occurs such that the tank monitor 168desires to close the product line shear valves 116, the tank monitor 168will cause the pilot control valve 390 to de-energize via thedispenser-powered microcontroller 412 in the DSM 170. This will vent anypilot pressure generated as a result of the vacuum level applied to thepilot control valve 390 through a vent 454 to atmosphere. This willcause the vacuum level to be lost in the pilot valve vacuum conduit 456thereby causing the pilot valves 458 to pneumatically switch to the N.O.position and causing their vents 459 to open to atmosphere and thevacuum actuator 186 to lose vacuum. This in turn causes the product lineshear valves 116 to close as previously discussed.

Further, any loss of vacuum in the dispenser sump interstitial space365, 27 will also pneumatically cause the product line shear valve 116to close irrespective of the tank monitor 168. This is because thevacuum actuator 186 of the product line shear valve 116 receives itsvacuum via vacuum conduit 448, 452, which also supplies the vacuum tothe dispenser sump interstitial space 365, 27.

Also, the shear tube 176 may be designed to assist in the detection ofan impact to the fuel dispenser 10 to cause the product line shearvalves 116 to close if the product line shear valve 116 does not shearproperly. The shear tube 176 may be constructed out of a rigid materialas opposed to a flexible material. For example, the shear tube 176 maybe constructed out of glass or other delicate material that is more liketo break in the event of an impact to the fuel dispenser 10. Thus, ifthe shear tube 176 breaks, the resulting loss of vacuum to the vacuumactuator 186 will cause the product line shear valve 116 to closeautomatically.

Communications Diagram

FIG. 16 illustrates a communications diagram of the secondarycontainment monitoring and control system according to the preferredembodiment. Many of the components illustrated therein have beenpreviously described and thus will not be repeated. The DSM 170 is shownas being powered by intrinsically safe power 468 through to the fueldispenser IS barrier 466. In this manner, the fuel dispenser 10 power,via its power supply 470, provides power to the dispenser-poweredmicrocontroller 412 as previously discussed.

An optional feature is also shown as the pilot control valve 390 openstatus. This status may be communicated from the interface electronicsof the dispenser-powered microcontroller 412 through an optic-coupler464 to the dispenser IS barrier 466. From there, the signal may becommunicated to a dispenser controller 429 residing within the dispenser429. The controller 429 may be the control system 46 as illustrated inFIG. 2. This status is used to know that the product line shear valves116 have been closed as the result of a leak or other condition aspreviously described. The dispenser controller 429 may use this statusto generate or communicate an alarm to the site controller 68, or takeother actions based on the status.

Shear Valve Controller

Because of the close pneumatic relationship between the operabilityvalve 430 and the pilot valve 458 to couple the vacuum level from the ofthe fuel dispenser piping interstitial space 123 to the product lineshear valve 116 and the vacuum path of the system, one embodiment of thepresent invention provides a shear valve controller than incorporatesboth of these components in a common mechanical package. This shearvalve controller 480 is illustrated in FIG. 17. The shear valvecontroller 480 contains both the operability valve 430 and the pilotvalve 458. The shear valve controller 480 contains a port 482 that isdesigned to couple to the interstitial space of the double-walledproduct line shear valve 116. This provides a convenient method ofcoupling the shear valve controller 480, and more particularly theoperability valve 430 and pilot valve 458 therein, to the fuel dispenserpiping interstitial space 123 to receive the vacuum as previouslydescribed. This is because the interstitial space of the double-walledshear valve is fluidly coupled to the fuel dispenser piping interstitialspace 123 when connected, as illustrated in FIGS. 4-6.

The product line shear valve 116 contains an orifice or port 474 on afinished surface 476 that is bored through the containment housing 164and is fluidly coupled to the interstitial space (not shown) of theproduct line shear valve 116 therein. The vacuum source port 482 iscoupled through an o-ring 484, which provides a seal between the shearvalve controller 480 and the finished surface 476 of the product lineshear valve 116. Mounting orifices 478 are provided on the finishedsurface to accept fasteners from the shear valve controller 480 tosecurely attach the shear valve controller 480 to the product line shearvalve 116.

The shear valve controller 480 also provides other ports to couple theoperability valve 430 and the pilot valve 458 to various flow paths, asillustrated in the pneumatic diagram of FIG. 15. A vacuum actuator port485 is provided as part of the shear valve controller 480 that isdesigned to couple the pilot valve 458 to the shear tube 176 to providethe vacuum source to the vacuum actuator 186. The shear valve controller480 also contains an end-of-zone valve port 442 that is designed tocouple to the vacuum conduit 431 to couple the operability valve 430 tothe end-of-zone switch 376. Lastly, the shear valve controller 480contains a pilot line port 487 that is adapted to couple the pilot valve458 inside the shear valve controller 480 to the pilot valve vacuumconduit 456 to receive the vacuum level from the pilot control valve390. These ports 482, 487, 485, 442 may contain a barbed surface inorder to securely couple to vacuum conduits as illustrated in thepneumatic diagram of FIG. 15.

FIG. 18 illustrates an exterior view of the shear valve controller 480to introduce and describes its components. The shear valve controller480 is comprised of a housing that is machined to provide the variousinternal flow paths to the operability valve 430 and the pilot valve 458therein. The shear valve controller 480 is machined to contain a vacuumsource orifice 492, a pilot valve orifice 494, a vacuum actuator orifice496, and an end-of-zone valve orifice 498, that are adapted to receivethe vacuum source port 482, the pilot line port 487, the vacuum actuatorport 485, and the end-of-zone valve port 442, respectively.

The operability valve 430 contains a screw cap 500 that is designed toallow a person to manually actuate and de-actuate the operability valve430. As previously discussed, actuation of the operability valve 430vents the vacuum source port 482 to atmosphere, thereby causing a lossof vacuum that will in turn cause a loss of vacuum at the vacuumactuator 186 and close the product line shear valve 116. To actuate theoperability valve 430, a person pushes down on the cap 500, which isspring-biased upward. This opens the vent 432 coupled to the operabilityvalve 430 to atmosphere and causes a loss of vacuum. In order tode-actuate the operability valve 430, the manual force applied to thecap 500 is released.

The cap 500 may also contain two oppositely opposing thumb andforefinger extensions 502 to allow a person to easily twist the cap 500back and forth. The cap 500 contains a locking mechanism 504 thatengages with a locking receiver 506 when the cap 500 is twistedcounterclockwise. The locking mechanism 504 can only engage with thelocking receiver 506 when a downward force is applied to the cap 500thereby actuating the operability valve 430. When engaged, this keepsthe operability valve 430 actuated without a person having to continueto push downward on the cap 500. When it is desired to de-actuate theoperability valve 430, the cap 500 is twisted clockwise, therebyallowing the cap 500 to be released in its upwardly biased directionthereby closing off the operability valve vent 432 to atmosphere.

FIG. 19 illustrates a cross-section view of the shear valve controller480 to better illustrate and describe the operation of the operabilityvalve 430 and the pilot valve 458 to provide their functions in thepneumatic system illustrated in FIG. 15. The cap 500 contains a caporifice 507 at the top. The cap orifice 507 is designed to allow afastener, such as a screw 508, to fit inside the cap orifice 507 to beflush or underneath the top plane of the cap 500 and secure the cap 500to an operability valve piston 510. The operability valve piston 510controls the flow of air between the end-of-zone valve orifice 498 andthe vacuum source orifice 492. The operability valve piston 510 containsan operability valve piston flute 512 having a piston flute top 518 andpiston flute bottom 520 that moves up and down when the cap 500 ispressed and released to open and block off the end-of-zone valve orifice498 from the vacuum source orifice 492. A cap spring 513 is placedinside and between the inside surface of the cap 500 and the top of theoperability valve piston 510 so that the cap 500 is spring biasedupward. The spring 513 engages with an operability valve piston plug 514that supports the operability valve piston 510 and moves the operabilityvalve piston 510 up and down when the operability valve piston plug 514is moved in kind. The operability valve piston plug 514 contains acircular groove to provide for an o-ring 516 to provide a tight seal ofthe operability valve piston plug 514 within the inner surface of theshear valve controller 480 housing.

When the operability valve 430 is not actuated, meaning the cap 500 isnot pushed down, the piston flute top 518 rests against the operabilityvalve piston plug 514 to provide a flow path between the end-of-zonevalve orifice 498 and the vacuum source orifice 492. This allows avacuum source applied to the vacuum source orifice 492 to also beapplied to the end-of-zone switch 376 and on to the dispenser sump 24,360 as previously discussed and illustrated in FIG. 15. When theoperability valve 430 is actuated, meaning the cap 500 is pushed down,the bottom of the piston flute bottom 520 rests against and blocks offthe vacuum source orifice 492. At the same time, the piston flute top518 moves down and off of the operability valve piston plug 514 and thusallows outside air to vent into the end-of-zone valve orifice 498. Thiswill cause a loss of vacuum that will be seen by the end-of-zone switch376, and thus the tank monitor 168 to in turn take the steps toeventually close the product line shear valve 116 as previouslydiscussed.

The right hand side of the shear valve controller 480 illustrated inFIG. 19 is the pilot valve 458 that controls the application of vacuumfrom the pilot valve vacuum conduit 456 coupled to the pilot valveorifice 494 to the vacuum actuator 186 via the vacuum actuator orifice496. In this manner, the vacuum source controlled by the pilot controlvalve 390 is pneumatically communicated to the pilot valve 458, which inturn actuates to pneumatically communicate the vacuum to the vacuumactuator 186. The pilot valve 458 is comprised of diaphragm 522 and adiaphragm spring 524. The diaphragm spring 524 pushes the diaphragm 522,which in turn pushes to the left on a pilot valve piston 526 having apilot valve piston flute 528. The pilot valve piston 526 is supported bya pilot valve piston plug 529 similar to the operability valve piston510. The pilot valve piston flute 528 contains a pilot valve pistonflute left section 530 and a pilot valve piston flute right section 532.When the diaphragm 522 is pushed by the diaphragm spring 524 to theleft, thereby applying a leftward force against the pilot valve piston526, the pilot valve piston flute left section 530 is pushed against theopening between the vacuum actuator orifice 496 and the end-of-zonevalve orifice 498 and the vacuum source orifice 492. Any vacuum that wasinside the vacuum actuator orifice 496 is vented through the pilot valvepiston flute 528 through a series of holes (not shown) in the diaphragmbase 534 to vent to atmosphere and release the vacuum actuator 186thereby closing the product line shear valve 116.

When a sufficient vacuum is applied to the pilot valve orifice 494 as aresult of a vacuum level generated and passed by the pilot control valve390 to the pilot valve conduit 456, this vacuum level will pull thediaphragm 522 to the right against its spring 524 biasing. This in turnwill pull the pilot valve piston 528 and the pilot valve piston flutesection 530, 530 to the right. This closes off the vent to atmospherethough the diaphragm base 534 and the coupling of the vacuum actuatororifice 496 to the vacuum source orifice 492 if the operability valve430 is not actuated to block of the flow path and vent the vacuumactuator orifice 496 to atmosphere. In this manner, the vacuum levelapplied to the vacuum actuator orifice 496 is applied to the vacuumactuator 186, which will in turn open the product line shear valve 1 16since vacuum levels are established and are being maintained.

Thus, the shear valve controller 480 provides a convenient method ofaccomplishing the pneumatic functions of the operability valve 430 andthe piston valve 458 in a convenient package. However, note that theshear valve controller 480 is not a requirement to accomplish thepresent invention.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present invention. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

1. A fuel dispenser that dispenses fuel received from a main fuel pipingfluidly coupled to a fuel storage tank, comprising: a housing containinga fuel-handling component area that contains at least one fuel-handlingcomponent; an internal fuel dispenser piping that is fluidly coupled tothe main fuel piping to receive fuel from the fuel storage tank; adouble-walled in-dispenser sump located inside the housing and below theat least one fuel-handling component, comprising: a main plate thatcaptures leaks from the at least one fuel handing-component; and asecondary plate coupled to and below the main plate such that anin-dispenser sump interstitial space is formed between the main plateand the secondary plate.
 2. The fuel dispenser of claim 1, wherein thein-dispenser sump interstitial space contains a port to allow avacuum-generating source to generate a vacuum level in the in-dispensersump interstitial space to monitor the vacuum level in the in-dispensersump interstitial space for leaks.
 3. The fuel dispenser of claim 1,further comprising a liquid sensor coupled to the main plate to detectthe presence of liquid fuel that leaks from the at least onefuel-handling component to the main plate.
 4. The fuel dispenser ofclaim 1, further comprising a liquid level sensor coupled to the mainplate to detect a level of liquid fuel that leaks from the at least onefuel-handling component to the main plate.
 5. The fuel dispenser ofclaim 1, further comprising an interstitial liquid sensor coupled to thein-dispenser sump interstitial space to detect a leak in thein-dispenser sump interstitial space indicative of a breach of the mainplate.
 6. The fuel dispenser of claim 1, wherein the main plate iscoupled to a catchment container where leaked fuel will collect whencaptured by the main plate.
 7. The fuel dispenser of claim 1, whereinthe main plate is sealed to internal walls of the housing.
 8. The fueldispenser of claim 1, wherein the main plate and secondary platecontains one or more aligned orifices that receive the internal fueldispenser piping to allow the internal fuel dispenser piping to carryfuel to the at least one fuel-handling component.
 9. The fuel dispenserof claim 8, wherein the one or more aligned orifices are sealed aroundthe internal fuel dispenser piping to prevent leaks of fuel captured bythe main plate from leaking below the double-walled in-dispenser sump.10. A fuel dispenser fuel-handling component leak capture and detectionsystem, comprising: a fuel dispenser containing a double-walledin-dispenser sump having an in-dispenser sump interstitial space,wherein the double-walled in-dispenser sump is located in the fueldispenser below at least one fuel-handling component in the fueldispenser that receives fuel from an internal fuel dispenser pipingcoupled to a main fuel piping that carries fuel from a fuel storagetank, wherein the double-walled in-dispenser sump captures leaks fromthe least one fuel-handling component; a vacuum-generating source thatis fluidly coupled to the in-dispenser interstitial space that generatesa vacuum level in the in-dispenser sump interstitial space; a pressuresensor coupled to the in-dispenser interstitial space; and a controlsystem coupled to the pressure sensor to monitor pressure variations inthe in-dispenser sump interstitial space to detect a loss in vacuum inthe in-dispenser sump interstitial space indicative of a leak.
 11. Thesystem of claim 10, further comprising a liquid sensor coupled to thein-dispenser sump and the control system, wherein the liquid sensor isadapted to detect the presence of liquid fuel that leaked from the atleast one fuel-handling component and communicate the presence of liquidfuel to the control system.
 12. The system of claim 10, furthercomprising a liquid level sensor coupled to the double-walledin-dispenser sump and the control system, wherein the liquid levelsensor is adapted to detect a level of fuel that leaked from the atleast one fuel-handling component and communicate the level to thecontrol system.
 13. The system of claim 10, further comprising aninterstitial liquid sensor coupled to the in-dispenser sump interstitialspace and the control system, wherein the interstitial liquid sensor isadapted to detect a leak in the in-dispenser sump interstitial spaceindicative of a leak in the double-walled in-dispenser sump andcommunicate the leak to the control system.
 14. The system of claim 10,wherein the vacuum-generating source is a submersible turbine pump,wherein a siphon on the submersible turbine pump is fluidly coupled tothe in-dispenser sump interstitial space.
 15. The system of claim 10,wherein the control system generates an alarm or report in response todetecting a leak in the in-dispenser sump interstitial space.
 16. Thesystem of claim 10, wherein the in-dispenser sump interstitial space iscoupled to at least one service station fuel-handling componentinterstitial space.
 17. The system of claim 16, wherein the at least oneservice station fuel-handling component interstitial space is either amain fuel piping interstitial space, a branch fuel piping interstitialspace, a shear valve interstitial space, an internal fuel dispenserpiping interstitial space, a vapor return piping interstitial space, afuel storage tank interstitial space, a submersible turbine pump sumpinterstitial space, a submersible turbine pump riser pipe interstitialspace, or a submersible turbine pump container interstitial space. 18.The system of claim 10, further comprising a control valve under controlof the control system coupled between the in-dispenser sump interstitialspace and the vacuum-generating source, wherein the control systemcontrols the control valve to couple the vacuum-generating source togenerate a vacuum level in the in-dispenser sump interstitial space. 19.The system of claim 18, wherein the control system closes the controlvalve to cut off the vacuum-generating source from the in-dispenser sumpinterstitial space once the vacuum level in the in-dispenser sumpinterstitial space reaches a threshold vacuum level.
 20. The system ofclaim 19, wherein the control system opens the control valve to allowthe vacuum-generating source to replenish the vacuum level in thein-dispenser sump interstitial space if the control system determinesthat the vacuum level has fallen below the threshold vacuum level. 21.The system of claim 16, wherein the at least one service stationfuel-handling component interstitial space is a double-walled shearvalve having a shear valve interstitial space.
 22. The system of claim10, wherein the control system actuates a pilot valve coupled to avacuum actuator that keeps the fuel flow path of a shear valve couplingthe main fuel piping to the internal fuel dispenser piping open when avacuum level is applied to the vacuum actuator, to create a loss ofvacuum applied to the vacuum actuator to close the shear valve inresponse to detecting a leak in the double-walled in-dispenser sump. 23.The system of claim 10, wherein the control system actuates a pilotvalve coupled to a vacuum actuator that keeps the fuel flow path of ashear valve open when a vacuum level is applied to the vacuum actuator,to create a loss of vacuum applied to the vacuum actuator to close theshear valve in response to detecting a leak in the double-walledin-dispenser sump.
 24. The system of claim 11, wherein the controlsystem actuates a pilot valve coupled to a vacuum actuator that keeps afuel flow path of a shear valve open when a vacuum level is applied tothe vacuum actuator, to create a loss of vacuum applied to the vacuumactuator to close the shear valve in response to receiving a signal fromthe liquid sensor indicating a presence of liquid in the double-walledin-dispenser sump.
 25. The system of claim 12, wherein the controlsystem actuates a pilot valve coupled to a vacuum actuator that keepsthe fuel flow path of a shear valve open when a vacuum level is appliedto the vacuum actuator, to create a loss of vacuum applied to the vacuumactuator to close the shear valve in response to receiving a signal fromthe interstitial liquid sensor indicating a level of fuel present in thedouble-walled in-dispenser sump.
 26. A method of monitoring anin-dispenser sump that captures leaked fuel from at least onefuel-handling component, comprising the steps of: generating a vacuumlevel in an in-dispenser sump interstitial space formed by adouble-walled in-dispenser sump, wherein the double-walled in-dispensersump is located in the fuel dispenser below the at least onefuel-handling component in the fuel dispenser that receives fuel from aninternal fuel dispenser piping coupled to a main fuel piping thatcarries fuel from a fuel storage tank, wherein the double-walledin-dispenser sump captures leaks from the at least one fuel-handlingcomponent; and monitoring the vacuum level in the in-dispenser sumpinterstitial space to determine if a leak exists in the in-dispensersump interstitial space.
 27. The method of claim 26, further comprisingdetecting the presence of fuel captured by the double-walledin-dispenser sump suing a liquid sensor.
 28. The method of claim 26,further comprising detecting a level of fuel captured by thedouble-walled in-dispenser sump using a liquid level sensor.
 29. Themethod of claim 26, further comprising detecting leaked fuel in thein-dispenser sump interstitial space using an interstitial liquidsensor.
 30. The method of claim 26, wherein the step of generating avacuum level comprises a submersible turbine pump generating a vacuumlevel in a siphon that is coupled to the in-dispenser sump interstitialspace.
 31. The method of claim 26, further comprising generating analarm or report in response to detecting a leak in the in-dispenser sumpinterstitial space.
 32. The method of claim 26, wherein the in-dispensersump interstitial space is coupled to at least one service stationfuel-handling component interstitial space.
 33. The method of claim 32,wherein the at least one service station fuel-handling componentinterstitial space is either a main fuel piping interstitial space, abranch fuel piping interstitial space, a shear valve interstitial space,an internal fuel dispenser piping interstitial space, a vapor returnpiping interstitial space, a fuel storage tank interstitial space, asubmersible turbine pump sump interstitial space, a submersible turbinepump riser pipe interstitial space, or a submersible turbine pumpcontainer interstitial space.
 34. The method of claim 26, furthercomprising controlling a control valve coupled between the in-dispensersump interstitial space and the vacuum-generating source to control thecoupling of the vacuum-generating source to the in-dispenser sumpinterstitial space to generate a vacuum level in the in-dispenser sumpinterstitial space.
 35. The method of claim 34, further comprisingclosing the control valve to cut off the vacuum-generating source fromthe in-dispenser sump interstitial space once the vacuum level in thein-dispenser sump interstitial space reaches a threshold vacuum level.36. The method of claim 35, further comprising opening the control valveafter the step of closing the control valve to allow thevacuum-generating source to replenish the vacuum level in thein-dispenser sump interstitial space after the vacuum level has fallenbelow the threshold vacuum level.
 37. The method of claim 32, whereinthe at least one service station fuel-handling component interstitialspace is a double-walled shear valve having a shear valve interstitialspace.
 38. The method of claim 26, further comprising actuating a pilotvalve coupled to a vacuum actuator that keeps a fuel flow path of ashear valve coupling the main fuel piping to the internal fuel dispenserpiping open when a vacuum level is applied to the vacuum actuator, tocreate a loss of vacuum applied to the vacuum actuator to close theshear valve in response to detecting a leak in the double-walledin-dispenser sump.
 39. The method of claim 27, further comprisingactuating a pilot valve coupled to a vacuum actuator that keeps a fuelflow path of a shear valve open when a vacuum level is applied to thevacuum actuator, to create a loss of vacuum applied to the vacuumactuator to close the shear valve in response to detecting the presenceof fuel in the double-walled in-dispenser sump.
 40. The method of claim28, further comprising actuating a pilot valve coupled to a vacuumactuator that keeps a fuel flow path of a shear valve open when a vacuumlevel is applied to the vacuum actuator, to create a loss of vacuumapplied to the vacuum actuator to close the shear valve in response toreceiving a signal from the liquid sensor indicating the level of fuelin the in-dispenser sump.
 41. The method of claim 29, further comprisingactuating a pilot valve coupled to a vacuum actuator that keeps the fuelflow path of a shear valve open when a vacuum level is applied to thevacuum actuator, to create a loss of vacuum applied to the vacuumactuator to close the shear valve in response to receiving a signal fromthe interstitial liquid sensor indicating leaked fuel present in thein-dispenser sump.